docs: finish onboarding/config heading consistency (#22537)

* docs: fix thinking link and add reasoning anchor reference

* docs(channels): rename LINE setup heading to onboarding

* docs(channels): normalize Nextcloud Talk onboarding headings

* docs(channels): use onboarding heading for Matrix setup

* docs(channels): standardize Discord onboarding heading

* docs(channels): standardize Telegram onboarding heading

* docs(channels): standardize WhatsApp onboarding heading

* docs(channels): rename iMessage onboarding and configuration sections

* docs(channels): rename Slack onboarding and configuration sections

* docs(channels): rename Signal onboarding heading

* docs(channels): standardize Nostr onboarding and configuration headings

* docs(channels): standardize Zalo onboarding and configuration headings

* docs(channels): standardize Twitch onboarding heading

* docs(channels): standardize Google Chat onboarding heading

* docs(channels): standardize Mattermost onboarding heading

* docs(channels): standardize Zalo Personal onboarding heading

* docs(channels): normalize Discord configuration heading

* docs(channels): standardize Microsoft Teams onboarding heading

* docs(channels): rename Signal configuration reference heading

* docs(channels): rename Matrix configuration reference heading

* docs(channels): normalize WhatsApp configuration heading

docs/channels/discord.md

@@ -963,7 +963,7 @@ openclaw logs --follow
   </Accordion>
 </AccordionGroup>
 
-## Configuration reference pointers
+## Configuration
 
 Primary reference:
 

docs/channels/matrix.md

@@ -270,7 +270,7 @@ Common failures:
 
 For triage flow: [/channels/troubleshooting](/channels/troubleshooting).
 
-## Configuration reference (Matrix)
+## Configuration
 
 Full configuration: [Configuration](/gateway/configuration)
 

docs/channels/msteams.md

@@ -38,7 +38,7 @@ OpenClaw will offer the local install path automatically.
 
 Details: [Plugins](/tools/plugin)
 
-## Quick setup (beginner)
+## Onboarding
 
 1. Install the Microsoft Teams plugin.
 2. Create an **Azure Bot** (App ID + client secret + tenant ID).

docs/channels/signal.md

@@ -290,7 +290,7 @@ For triage flow: [/channels/troubleshooting](/channels/troubleshooting).
 - Keep `channels.signal.dmPolicy: "pairing"` unless you explicitly want broader DM access.
 - SMS verification is only needed for registration or recovery flows, but losing control of the number/account can complicate re-registration.
 
-## Configuration reference (Signal)
+## Configuration
 
 Full configuration: [Configuration](/gateway/configuration)
 

docs/channels/whatsapp.md

@@ -422,7 +422,7 @@ Behavior notes:
   </Accordion>
 </AccordionGroup>
 
-## Configuration reference pointers
+## Configuration
 
 Primary reference: