[chore] adding an issue number in the changelog (#10843)

This will reference the same issue instead of needing to create a PR and
add it to the changelog. Creating a PR and then updating it is not
allowed because of the branch protection permissions.

Signed-off-by: Alex Boten <223565+codeboten@users.noreply.github.com>

.github/workflows/generate-semantic-conventions-pr.yaml

@@ -85,7 +85,7 @@ jobs:
           GH_TOKEN: ${{ secrets.OPENTELEMETRYBOT_GITHUB_TOKEN }}
         run: |
           message="Add semantic conventions version $VERSION"
-          body="Add semantic conventions version \`$VERSION\`."
+          body="Add semantic conventions version \`$VERSION\`. Related to #10842"
           branch="opentelemetrybot/add-semantic-conventions-${VERSION}"
 
           git checkout -b $branch
@@ -96,7 +96,7 @@ jobs:
           change_type: enhancement
           component: semconv
           note: Add semantic conventions version $VERSION
-          issues: [ $pull_request_number ]
+          issues: [10842]
           EOF
 
           git add .chloggen/semconv-$VERSION.yaml