document default disabled micrometer instrumentation (#13492)

Co-authored-by: Jay DeLuca <[email protected]>

Author: SylvainJuge

docs/supported-libraries.md

@@ -101,7 +101,7 @@ These are the supported libraries and frameworks:
 | [Log4j 1](https://logging.apache.org/log4j/1.2/)                                                                                            | 1.2+                               | N/A                                                                                                                                                                                                                                                                                                                                                                                     | none                                                                                                                                    |
 | [Log4j 2](https://logging.apache.org/log4j/2.x/)                                                                                            | 2.11+                              | [opentelemetry-log4j-appender-2.17](../instrumentation/log4j/log4j-appender-2.17/library),<br>[opentelemetry-log4j-context-data-2.17-autoconfigure](../instrumentation/log4j/log4j-context-data/log4j-context-data-2.17/library-autoconfigure)                                                                                                                                          | none                                                                                                                                    |
 | [Logback](http://logback.qos.ch/)                                                                                                           | 1.0+                               | [opentelemetry-logback-appender-1.0](../instrumentation/logback/logback-appender-1.0/library),<br>[opentelemetry-logback-mdc-1.0](../instrumentation/logback/logback-mdc-1.0/library)                                                                                                                                                                                                   | none                                                                                                                                    |
-| [Micrometer](https://micrometer.io/)                                                                                                        | 1.5+                               | [opentelemetry-micrometer-1.5](../instrumentation/micrometer/micrometer-1.5/library)                                                                                                                                                                                                                                                                                                    | none                                                                                                                                    |
+| [Micrometer](https://micrometer.io/)                                                                                                        | 1.5+ (disabled by default)         | [opentelemetry-micrometer-1.5](../instrumentation/micrometer/micrometer-1.5/library)                                                                                                                                                                                                                                                                                                    | none                                                                                                                                    |
 | [MongoDB Driver](https://mongodb.github.io/mongo-java-driver/)                                                                              | 3.1+                               | [opentelemetry-mongo-3.1](../instrumentation/mongo/mongo-3.1/library)                                                                                                                                                                                                                                                                                                                   | [Database Client Spans], [Database Client Metrics]&nbsp;[6]                                                                             |
 | [MyBatis](https://mybatis.org/mybatis-3/)                                                                                                   | 3.2+                               | N/A                                                                                                                                                                                                                                                                                                                                                                                     | none                                                                                                                                    |
 | [Netty HTTP codec [5]](https://github.com/netty/netty)                                                                                      | 3.8+                               | [opentelemetry-netty-4.1](../instrumentation/netty/netty-4.1/library)                                                                                                                                                                                                                                                                                                                   | [HTTP Client Spans], [HTTP Client Metrics], [HTTP Server Spans], [HTTP Server Metrics]                                                  |
@@ -230,12 +230,16 @@ These are the JVMs and operating systems that the integration tests are run agai
 
 ## Disabled instrumentations
 
-Some instrumentations can produce too many spans and make traces very noisy.
+Some instrumentations can produce too many spans and metrics and thus create a lot of noise.
 For this reason, the following instrumentations are disabled by default:
 
 - `jdbc-datasource` which creates spans whenever the `java.sql.DataSource#getConnection` method is called.
 - `dropwizard-metrics` which might create a very low quality metrics data, because of lack of label/attribute support
   in the Dropwizard metrics API.
+- `micrometer` which might create high number of metrics due to being broadly used in libraries.
 
 To enable them, add the `otel.instrumentation.<name>.enabled` system property:
-`-Dotel.instrumentation.jdbc-datasource.enabled=true`
+
+- `-Dotel.instrumentation.jdbc-datasource.enabled=true`
+- `-Dotel.instrumentation.dropwizard-metrics.enabled=true`
+- `-Dotel.instrumentation.micrometer.enabled=true`