docs: small tweaks:

Author: lukegalbraithrussell

docs/content/migration/migrating-to-v5.md

@@ -1,8 +1,4 @@
----
-title: Migrating to v5.x
----
-
-# Migration Guide (v4 to v5)
+# Migrating to v5.x
 
 This tutorial will guide you through the process of updating your app from using the `@slack/client` package (`v4.x`)
 to using the new, improved, and independent packages, starting with `v5.0.0`.

docs/content/migration/migrating-to-v6.md

@@ -1,8 +1,4 @@
----
-title: Migrating to v6.x
----
-
-# Migration Guide (v5 to v6)
+# Migrating to v6.x
 
 The following packages have been updated in the release being dubbed as `v6`:
 * `@slack/[email protected]`

docs/content/packages/web-api.md

@@ -1,8 +1,8 @@
 ---
-title: Web API
 slug: /web-api
 ---
 
+# Web API
 
 The `@slack/web-api` package contains a simple, convenient, and configurable HTTP client for making requests to Slack's
 [Web API](https://api.slack.com/web). Use it in your app to call any of the over 130