build: add ngcc as a valid commit message scope

CONTRIBUTING.md

@@ -233,6 +233,7 @@ There are currently a few exceptions to the "use package name" rule:
 * **docs-infra**: used for docs-app (angular.io) related changes within the /aio directory of the
   repo
 * **ivy**: used for changes to the [Ivy renderer](https://github.com/angular/angular/issues/21706).
+* **ngcc**: used for changes to the [Angular Compatibility Compiler](./packages/compiler-cli/ngcc/README.md)
 * none/empty string: useful for `style`, `test` and `refactor` changes that are done across all
   packages (e.g. `style: add missing semicolons`) and for docs changes that are not related to a
   specific package (e.g. `docs: fix typo in tutorial`).

docs/TRIAGE_AND_LABELS.md

@@ -12,7 +12,6 @@ The owner of the component is then responsible for the secondary / component-lev
 The caretaker should be able to determine which component the issue belongs to.
 The components have a clear piece of source code associated with it within the `/packages/` folder of this repo.
 
-* `comp: docs-infra` - the angular.io application and docs-related tooling
 * `comp: animations`
 * `comp: bazel` - @angular/bazel rules
 * `comp: benchpress`
@@ -21,6 +20,8 @@ The components have a clear piece of source code associated with it within the `
 * `comp: core & compiler` - because core, compiler, compiler-cli and
   browser-platforms are very intertwined, we will be treating them as one
 * `comp: ivy` - a subset of core representing the new Ivy renderer.
+* `comp: ngcc` - a subset of ivy representing the [Angular Compatibility Compiler](../packages/compiler-cli/ngcc/README.md)
+* `comp: docs-infra` - the angular.io application and docs-related tooling
 * `comp: elements`
 * `comp: forms`
 * `comp: http`

tools/validate-commit-message/commit-message.json

@@ -27,6 +27,7 @@
     "http",
     "ivy",
     "language-service",
+    "ngcc",
     "platform-browser",
     "platform-browser-dynamic",
     "platform-server",