Define CODECOV token (#6186)

.github/workflows/build.yml

@@ -77,6 +77,8 @@ jobs:
 
       - uses: codecov/codecov-action@v3
         if: ${{ matrix.coverage }}
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
 
       - uses: actions/upload-artifact@v4
         if: ${{ matrix.coverage }}

RELEASING.md

@@ -77,7 +77,7 @@ Create a PR against the main branch with the changes.
 
 ## Credentials
 
-The following credentials are required for publishing (and automatically set in Github Actions):
+The following credentials are required for building or publishing (and automatically set in Github Actions):
 
 * `GPG_PRIVATE_KEY` and `GPG_PASSWORD`: GPG private key and password for signing.
 * `SONATYPE_USER` and `SONATYPE_KEY`: Sonatype username and password.
@@ -89,6 +89,9 @@ The following credentials are required for publishing (and automatically set in
   * To obtain `SONATYPE_USER` and `SONATYPE_KEY` for your account, login
     to [oss.sonatype.org](https://oss.sonatype.org/) and navigate to Profile -> User Token -> Access
     User Token.
+* `CODECOV_TOKEN`: Token used for uploading codecov reports. Each maintainer can obtain their own
+  credential from codecov as
+  described [here](https://docs.codecov.com/docs/adding-the-codecov-token#github-actions).
 
 Additionally, credentials are stored with maintainers via
 the [OpenTelemetry 1Password](https://opentelemetry.1password.com/signin) account. The following