Add CIFuzz documentation on how to run jobs on certain branches, paths (#4113)

docs/getting-started/continuous_integration.md

@@ -79,7 +79,6 @@ jobs:
 ```
 
 
-
 ### Optional configuration
 
 #### Configurable Variables
@@ -136,6 +135,54 @@ jobs:
 {% endraw %}
 ```
 
+#### Branches and paths
+
+You can make CIFuzz trigger only on certain branches or paths by following the
+instructions [here](https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions).
+For example, the following code can used to trigger CIFuzz only on changes to
+C/C++ code residing on master and release branches:
+
+```yaml
+name: CIFuzz
+on:
+  pull_request:
+    branches: 
+      - master
+      - 'releases/**'
+    paths:
+      - '**.c'
+      - '**.cc'
+      - '**.cpp'
+      - '**.cxx'
+      - '**.h'
+jobs:
+ Fuzzing:
+   runs-on: ubuntu-latest
+   steps:
+   - name: Build Fuzzers
+     id: build
+     uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@master
+     with:
+       oss-fuzz-project-name: 'example'
+       dry-run: false
+   - name: Run Fuzzers
+     uses: google/oss-fuzz/infra/cifuzz/actions/run_fuzzers@master
+     with:
+       oss-fuzz-project-name: 'example'
+       fuzz-seconds: 600
+       dry-run: false
+   - name: Upload Crash
+     uses: actions/upload-artifact@v1
+     if: failure() && steps.build.outcome == 'success'
+     with:
+       name: artifacts
+       path: ./out/artifacts
+```
+
+You can checkout CIFuzz configs for OSS-Fuzz projects. Example -
+[systemd](https://github.com/systemd/systemd/blob/master/.github/workflows/cifuzz.yml),
+[curl](https://github.com/curl/curl/blob/master/.github/workflows/fuzz.yml).
+
 ## Understanding results
 
 The results of CIFuzz can be found in two different places.