feat(ruby): Add auto instrumentation docs (#8574)

src/platforms/ruby/common/performance/instrumentation/automatic-instrumentation.mdx

@@ -0,0 +1,26 @@
+---
+title: Automatic Instrumentation
+sidebar_order: 10
+supported:
+  - ruby
+  - ruby.rails
+description: "Learn what instrumentation automatically captures transactions."
+redirect_from:
+  - /performance/included-instrumentation
+---
+
+Many integrations for popular frameworks automatically capture transactions. If you use have any of the following frameworks set up for Sentry error reporting and use the relevant Sentry gem, you will start to see traces immediately:
+
+- Ruby on Rails (`sentry-rails`)
+- Sidekiq (`sentry-sidekiq`)
+- Delayed Job (`sentry-delayed_job`)
+- Resque (`sentry-resque`)
+
+Spans are instrumented for the following operations within a transaction:
+
+- Database queries in Rails that use `ActiveRecord`
+  - includes common database systems such as Postgres and MySQL
+- Outgoing HTTP requests made with `Net::HTTP`
+- Redis operations
+
+Spans are only created within an existing transaction. If you're not using any of the supported frameworks, you'll need to <PlatformLink to="/performance/instrumentation/custom-instrumentation/">create transactions manually</PlatformLink>.