doc: use pull request title pattern for issues too (#4057)

Co-authored-by: Alec Charbonneau <[email protected]>

CONTRIBUTING.md

@@ -11,13 +11,20 @@ Check out the [Stellar Contribution Guide](https://github.com/stellar/.github/bl
 * Use the present tense ("Add feature" not "Added feature")
 * Use the imperative mood ("Move cursor to..." not "Moves cursor to...")
 
-### Pull Requests
+### Issues
 
-* PR titles start with:
-  * The package name most affected, ex. `services/horizon: fix...`.
+* Issues and PR titles start with:
+  * The package name most affected, ex. `ingest: fix...`.
+  * Or, for services and tools, the service most affected, ex. `services/horizon: fix...`, `services/ticker: add...`
   * Or, multiple package names separated by a comma when the fix addresses multiple packages worth noting, ex. `services/horizon, services/friendbot: fix...`.
-  * Or, `all:` when changes are broad, ex. `all: update...`.
-  * Or, `doc:` when changes are isolated to non-code documentation not limited to a single package.
+  * Or, `all:` when changes or an issue are broad, ex. `all: update...`.
+  * Or, `doc:` when changes or an issue are isolated to non-code documentation not limited to a single package.
+* Label issues with `bug` if they're clearly a bug.
+* Label issues with `feature request` if they're a feature request.
+
+### Pull Requests
+
+* PR titles follow the same rules as described in the [Issues](#Issues) section above.
 * PRs must update the [CHANGELOG](CHANGELOG.md) with a small description of the change
 * PRs are merged into master or release branch using squash merge
 * Carefully think about where your PR fits according to [semver](https://semver.org). Target it at master if it’s only a patch change, otherwise if it contains breaking change or significant feature additions, set the base branch to the next major or minor release.