docs: Update headings for new style rule (#3396)

* docs: Update headings for new style rule

* docs: Fix headings - Get started

* docs: Fix headings - Install

* docs: Fix headings - Concepts

* docs: Fix typos

* docs: Fix headings - Configuration

* docs: Fix headings - Operations

* docs: Fix headings - Troubleshoot

* docs: Fix headings - Clients and Develop

* docs: Fix headings - HCP and ENT

* docs: Fix headings - Release notes

* docs: Fix typos

* docs: Fix capitalization in TOC

website/content/docs/developing/building.mdx

@@ -35,7 +35,7 @@ environment variable to set this. Example: `$ GOOS=linux GOARCH=amd64 make insta
 
 For more details, please consult the [Boundary project on GitHub](https://github.com/hashicorp/boundary#build-and-start-boundary-in-dev-mode).
 
-## Troubleshooting
+## Troubleshoot
 
 UI assets are built inside a Docker container. If this build step fails, try
 increasing memory and swap available to Docker.

website/content/docs/developing/ui.mdx

@@ -9,7 +9,7 @@ description: Develop the Boundary user interface
 For detailed instructions and the most up-to-date information on developing the
 Boundary admin UI, please consult [the project README on GitHub](https://github.com/hashicorp/boundary-ui).
 
-## Run a local fork of the UI locally in Dev Mode
+## Run a local fork of the UI locally in dev mode
 
 If you're developing the Boundary UI locally you can point a dev mode server at a
 local checkout of the repo without building it into the binary. We call this