docs: add errors to message posting examples

Co-Authored-By: Claude <svc-devxp-claude@slack-corp.com>

Author: zimeg

example-workflows/Technique_2_Slack_API_Method/invite.yml

@@ -24,6 +24,7 @@ jobs:
       - name: Send the issue link into the Slack channel
         uses: slackapi/slack-github-action@v2.1.1
         with:
+          errors: true
           method: chat.postMessage # https://docs.slack.dev/reference/methods/chat.postMessage/
           token: ${{ secrets.SLACK_BOT_TOKEN }}
           payload: |

example-workflows/Technique_4_Slack_CLI_Command/collaborators.yml

@@ -51,6 +51,7 @@ jobs:
         if: ${{ steps.email.outputs.ok }}
         uses: slackapi/slack-github-action@v2
         with:
+          errors: true
           method: chat.postMessage # https://docs.slack.dev/reference/methods/chat.postMessage/
           token: ${{ secrets.SLACK_BOT_TOKEN }}
           payload: |

example-workflows/Technique_4_Slack_CLI_Command/deploy.yml

@@ -24,6 +24,7 @@ jobs:
       - name: Post a deployment message
         uses: slackapi/slack-github-action@v2
         with:
+          errors: true
           method: chat.postMessage
           token: ${{ secrets.SLACK_BOT_TOKEN }}
           payload: |