Make trivial adjustments to comments in "Check Certificates" workflow

No functional change, and neither is necessarily superior, but this is how it is in the "template", and so it must be
here as well.

Author: per1234

.github/workflows/check-certificates.yml

@@ -9,13 +9,13 @@ on:
     paths:
       - ".github/workflows/check-certificates.ya?ml"
   schedule:
-    # run every 10 hours
+    # Run every 10 hours.
     - cron: "0 */10 * * *"
   workflow_dispatch:
   repository_dispatch:
 
 env:
-  # Begin notifications when there are less than this many days remaining before expiration
+  # Begin notifications when there are less than this many days remaining before expiration.
   EXPIRATION_WARNING_PERIOD: 30
 
 jobs:
@@ -31,17 +31,18 @@ jobs:
 
       matrix:
         certificate:
-          - identifier: macOS signing certificate # Text used to identify the certificate in notifications
-            certificate-secret: INSTALLER_CERT_MAC_P12  # The name of the secret that contains the certificate
-            password-secret: INSTALLER_CERT_MAC_PASSWORD  # The name of the secret that contains the certificate password
+          # Additional certificate definitions can be added to this list.
+          - identifier: macOS signing certificate # Text used to identify certificate in notifications.
+            certificate-secret: INSTALLER_CERT_MAC_P12  # Name of the secret that contains the certificate.
+            password-secret: INSTALLER_CERT_MAC_PASSWORD  # Name of the secret that contains the certificate password.
           - identifier: Windows signing certificate
             certificate-secret: INSTALLER_CERT_WINDOWS_PFX
             password-secret: INSTALLER_CERT_WINDOWS_PASSWORD
 
     steps:
       - name: Set certificate path environment variable
         run: |
-          # See: https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-commands-for-github-actions#setting-an-environment-variable
+          # See: https://docs.github.com/en/actions/reference/workflow-commands-for-github-actions#setting-an-environment-variable
           echo "CERTIFICATE_PATH=${{ runner.temp }}/certificate.p12" >> "$GITHUB_ENV"
       - name: Decode certificate
         env:
@@ -60,7 +61,6 @@ jobs:
             echo "::error::Verification of ${{ matrix.certificate.identifier }} failed!!!"
             exit 1
           )
-      # See: https://github.com/rtCamp/action-slack-notify
       - name: Slack notification of certificate verification failure
         if: failure()
         uses: rtCamp/action-slack-notify@v2
@@ -98,7 +98,7 @@ jobs:
             )
           )"
           DAYS_BEFORE_EXPIRATION="$((($(date --utc --date="$EXPIRATION_DATE" +%s) - $(date --utc +%s)) / 60 / 60 / 24))"
-          # Display the expiration information in the log
+          # Display the expiration information in the log.
           echo "Certificate expiration date: $EXPIRATION_DATE"
           echo "Days remaining before expiration: $DAYS_BEFORE_EXPIRATION"
           echo "::set-output name=days::$DAYS_BEFORE_EXPIRATION"
@@ -110,7 +110,7 @@ jobs:
             exit 1
           fi
       - name: Slack notification of pending certificate expiration
-        # Don't send spurious expiration notification if verification fails
+        # Don't send spurious expiration notification if verification fails.
         if: failure() && steps.check-expiration.outcome == 'failure'
         uses: rtCamp/action-slack-notify@v2
         env: