chore(java): Add docs on how to use tracePropagationTargets (#14752)

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Based on iOS docs:
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---------

Co-authored-by: Alexander Dinauer <[email protected]>

Author: markushi

docs/platforms/android/tracing/trace-propagation/index.mdx

@@ -32,3 +32,34 @@ If you run any JavaScript applications in your distributed system, make sure tha
 <PlatformContent includePath="distributed-tracing/how-to-use/" />
 
 Remember that in order to propagate trace information through your whole distributed system, you have to use Sentry in all of the involved services and applications. Take a look at the respective SDK documentation to learn how distributed tracing can be enabled for each platform.
+
+### tracePropagationTargets
+
+The Android SDK will attach the `sentry-trace` and `baggage` headers to all outgoing requests by default. To narrow
+this down to only specific URLs, add those URLs to the `tracePropagationTargets` allowlist, (you can use both
+strings and regexes). The SDK will then only attach the `sentry-trace` and `baggage` headers to outgoing requests matching the allowlist.
+
+<Alert>
+The `tracePropagationTargets` option can contain full URLs (e.g. `"https://api.myproject.org/request/path"`), sub-strings (e.g. `"api.myproject.org"`) or regular expressions (e.g. `"https://[\w]*\.myproject\.org/.*"`).
+</Alert>
+
+Since the value of `tracePropagationTargets` is `".*"` by default, tracing headers are attached to all requests unless otherwise specified.
+
+```java {tabTitle:Java}
+SentryAndroid.init(context, options -> {
+    final ArrayList<String> tracePropagationTargets = new ArrayList<>();
+    tracePropagationTargets.add("https://api.myproject.org/");
+
+    options.setDsn("___PUBLIC_DSN___");
+    options.setTracePropagationTargets(tracePropagationTargets);
+});
+```
+
+```kotlin {tabTitle:Kotlin}
+SentryAndroid.init(context, { options ->
+    options.setDsn("___PUBLIC_DSN___")
+    options.setTracePropagationTargets(listOf(
+        "https://api.myproject.org/"
+    ))
+})
+```

docs/platforms/java/common/tracing/trace-propagation/index.mdx

@@ -32,3 +32,34 @@ If you run any JavaScript applications in your distributed system, make sure tha
 <PlatformContent includePath="distributed-tracing/how-to-use/" />
 
 Remember that in order to propagate trace information through your whole distributed system, you have to use Sentry in all of the involved services and applications. Take a look at the respective SDK documentation to learn how distributed tracing can be enabled for each platform.
+
+### tracePropagationTargets
+
+The Java SDK will attach the `sentry-trace` and `baggage` headers to all outgoing requests by default. To narrow
+this down to only specific URLs, add those URLs to the `tracePropagationTargets` allowlist, (you can use both
+strings and regexes). The SDK will then only attach the `sentry-trace` and `baggage` headers to outgoing requests matching the allowlist.
+
+<Alert>
+The `tracePropagationTargets` option can contain full URLs (e.g. `"https://api.myproject.org/request/path"`), sub-strings (e.g. `"api.myproject.org"`) or regular expressions (e.g. `"https://[\w]*\.myproject\.org/.*"`).
+</Alert>
+
+Since the value of `tracePropagationTargets` is `".*"` by default, tracing headers are attached to all requests unless otherwise specified.
+
+```java {tabTitle:Java}
+Sentry.init(context, options -> {
+    final ArrayList<String> tracePropagationTargets = new ArrayList<>();
+    tracePropagationTargets.add("https://api.myproject.org/");
+
+    options.setDsn("___PUBLIC_DSN___");
+    options.setTracePropagationTargets(tracePropagationTargets);
+});
+```
+
+```kotlin {tabTitle:Kotlin}
+Sentry.init(context, { options ->
+    options.setDsn("___PUBLIC_DSN___")
+    options.setTracePropagationTargets(listOf(
+        "https://api.myproject.org/"
+    ))
+})
+```