docs(drains): add OpenTelemetry Collector guides (#15755)

This pull request adds a new section to the drains documentation,
providing guides for forwarding logs from various sources to Sentry
using the OpenTelemetry Collector. These guides help users configure log
forwarding from AWS CloudWatch, Kafka, Nginx, Syslog, and Windows Event
Logs.

Documentation updates:

* Added an "OpenTelemetry Collector guides" section to the drains
documentation, including links to guides for forwarding logs from AWS
CloudWatch, Kafka, Nginx, Syslog, and Windows Event Logs to Sentry.

<img width="2110" height="1042" alt="image"
src="https://github.com/user-attachments/assets/c4644499-3db0-49c4-a256-0023dce06cc7"
/>

Author: KyleTryon

docs/product/drains/index.mdx

@@ -40,6 +40,10 @@ Sending error events via drains or forwarders is not currently supported. To cap
 | [Vector](/product/drains/integration/vector/)                                                 |  ✅  |   ❌   |
 | [Fluent Bit](/product/drains/integration/fluentbit/)                                          |  ✅  |   ✅   |
 
+### OpenTelemetry Collector guides
+
+<Include name="opentelemetry-collector-guides.mdx" />
+
 ## Learn More
 
 - [Logs](/product/explore/logs/): View, search, and analyze logs in Sentry

docs/product/drains/integration/opentelemetry-collector.mdx

@@ -142,8 +142,4 @@ service:
 
 These guides show you how to leverage the OpenTelemetry Collector to send traces and logs to Sentry from different sources.
 
-- [Forwarding AWS CloudWatch Logs to Sentry](/product/drains/otlp-guides/aws-cloudwatch/)
-- [Forwarding Logs and Traces from Kafka to Sentry](/product/drains/otlp-guides/kafka/)
-- [Forwarding Nginx Logs to Sentry](/product/drains/otlp-guides/nginx/)
-- [Forwarding Syslog Messages to Sentry](/product/drains/otlp-guides/syslog/)
-- [Forwarding Windows Event Logs to Sentry](/product/drains/otlp-guides/windows-events/)
+<Include name="opentelemetry-collector-guides.mdx" />

includes/opentelemetry-collector-guides.mdx

@@ -0,0 +1,6 @@
+- [Forwarding AWS CloudWatch Logs to Sentry](/product/drains/otlp-guides/aws-cloudwatch/)
+- [Forwarding Logs and Traces from Kafka to Sentry](/product/drains/otlp-guides/kafka/)
+- [Forwarding Nginx Logs to Sentry](/product/drains/otlp-guides/nginx/)
+- [Forwarding Syslog Messages to Sentry](/product/drains/otlp-guides/syslog/)
+- [Forwarding Windows Event Logs to Sentry](/product/drains/otlp-guides/windows-events/)
+