Add docs for network change (open-telemetry#789)

* add docs for network change

* Update instrumentation/network/README.md

Co-authored-by: Manoel Aranda Neto <[email protected]>

---------

Co-authored-by: Manoel Aranda Neto <[email protected]>

Author: breedx-splk

README.md

@@ -54,7 +54,7 @@ Some of the additional features provided include:
 
 * [Crash reporting](./instrumentation/crash/)
 * [ANR detection](./instrumentation/anr/)
-* Network change detection
+* [Network change detection](./instrumentation/network/)
 * Android [Activity lifecycle instrumentation](./instrumentation/activity/)
 * Android Fragment lifecycle monitoring
 * Access to the OpenTelemetry APIs for manual instrumentation

instrumentation/network/README.md

@@ -0,0 +1,29 @@
+
+# Network Change Instrumentation
+
+Status: experimental
+
+Android applications are typically deployed on mobile devices. These mobile devices
+have the ability to move between networks, and sometimes a network change can
+have an impact on application performance characteristics. This instrumentation
+will generate telemetry when the network changes, as detected
+via [ConnectivityManager.NetworkCallback](https://developer.android.com/reference/android/net/ConnectivityManager.NetworkCallback).
+
+This instrumentation only generates telemetry when the application is in the foreground,
+not when the application is backgrounded.
+
+## Telemetry
+
+This instrumentation produces the following telemetry:
+
+### Network Change
+
+* Type: Span
+* Name: `network.change`
+* Description: This zero-duration span is started and ended when a network change is detected.
+* Attributes:
+    * `network.status`: One of `lost` or `available`.
+    * `network.connection.type` (semconv) one of `cell`, `wifi`, `wired`, `unavailable`, `unknown`, `vpn`.
+
+Note: This instrumentation supports additional user-configurable `AttributeExtractors` that
+may set additional attributes when given a `CurrentNetwork` instance.