Auto merge of #12630 - epage:ci, r=arlosi

docs(guide): Apply feedback on CI

See #12382

src/doc/src/guide/continuous-integration.md

@@ -4,7 +4,7 @@
 
 A basic CI will build and test your projects:
 
-## GitHub Actions
+### GitHub Actions
 
 To test your package on GitHub Actions, here is a sample `.github/workflows/ci.yml` file:
 
@@ -38,7 +38,7 @@ jobs:
 
 This will test all three release channels (note a failure in any toolchain version will fail the entire job). You can also click `"Actions" > "new workflow"` in the GitHub UI and select Rust to add the [default configuration](https://github.com/actions/starter-workflows/blob/main/ci/rust.yml) to your repo. See [GitHub Actions documentation](https://docs.github.com/en/actions) for more information.
 
-## GitLab CI
+### GitLab CI
 
 To test your package on GitLab CI, here is a sample `.gitlab-ci.yml` file:
 
@@ -67,7 +67,7 @@ breakage in nightly will not fail your overall build. Please see the
 [GitLab CI documentation](https://docs.gitlab.com/ce/ci/yaml/index.html) for more
 information.
 
-## builds.sr.ht
+### builds.sr.ht
 
 To test your package on sr.ht, here is a sample `.build.yml` file.
 Be sure to change `<your repo>` and `<your project>` to the repo to clone and
@@ -139,7 +139,7 @@ Some potential solutions include:
   - Only uses the resources necessary
   - Can configure the frequency to balance CI resources and coverage of dependency versions
 
-An example CI job to verify latest dependencies, using Github Actions:
+An example CI job to verify latest dependencies, using GitHub Actions:
 ```yaml
 jobs:
   latest_deps: