docs(changelog): Expand code-mappings upload entry with details

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: romtsn

CHANGELOG.md

@@ -4,7 +4,10 @@
 
 ### New Features ✨
 
-- Add `sentry-cli code-mappings upload` command to bulk upload code mappings from a JSON file, with automatic git inference for repository name and default branch ([#3207](https://github.com/getsentry/sentry-cli/pull/3207), [#3208](https://github.com/getsentry/sentry-cli/pull/3208), [#3209](https://github.com/getsentry/sentry-cli/pull/3209), [#3210](https://github.com/getsentry/sentry-cli/pull/3210)).
+- Add `sentry-cli code-mappings upload` command to bulk upload code mappings from a JSON file ([#3207](https://github.com/getsentry/sentry-cli/pull/3207), [#3208](https://github.com/getsentry/sentry-cli/pull/3208), [#3209](https://github.com/getsentry/sentry-cli/pull/3209), [#3210](https://github.com/getsentry/sentry-cli/pull/3210)).
+  - Code mappings link stack trace paths (e.g. `com/example/module`) to source paths in your repository (e.g. `src/main/java/com/example/module`), enabling Sentry to display source context and link directly to your code from error stack traces.
+  - Repository name and default branch are automatically inferred from your local git remotes, or can be specified explicitly with `--repo` and `--default-branch`.
+  - Large mapping files are automatically split into batches for upload.
 
 ### Internal Changes 🔧