AW docs: format link anchor in android_build_instructions

Docs only, no change to production code.

This removes backticks on "Install depot_tools" to render better in the
table of contents (gitiles strips code-formatted text from TOC) and have
more sensible fragment link anchors. This updates all markdown files
dependent on the link anchor.

Bug: 918221
Test: Upload to gerrit > open file > click "gitiles"
Change-Id: Id8ec00af6a796212bbc6ceebd5c3d20ca80da920
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1656375
Auto-Submit: Nate Fischer <ntfschr@chromium.org>
Commit-Queue: Paul Miller <paulmiller@chromium.org>
Reviewed-by: Paul Miller <paulmiller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#668549}

android_webview/docs/build-instructions.md

@@ -26,7 +26,7 @@ See general Android instructions for:
 
 * [System
   requirements](/docs/android_build_instructions.md#System-requirements)
-* [Installing `depot_tools`](/docs/android_build_instructions.md#install)
+* [Installing `depot_tools`](/docs/android_build_instructions.md#Install-depot_tools)
 * [Getting the code](/docs/android_build_instructions.md#Get-the-code) **or**
   [converting a Linux
   checkout](/docs/android_build_instructions.md#Converting-an-existing-Linux-checkout)

android_webview/docs/quick-start.md

@@ -23,7 +23,8 @@ See general Android instructions for:
 
 * [System
   requirements](/docs/android_build_instructions.md#System-requirements)
-* [Installing `depot_tools`](/docs/android_build_instructions.md#install)
+* [Installing
+  `depot_tools`](/docs/android_build_instructions.md#Install-depot_tools)
 * [Getting the code](/docs/android_build_instructions.md#Get-the-code) **or**
   [converting a Linux
   checkout](/docs/android_build_instructions.md#Converting-an-existing-Linux-checkout)

docs/android_build_instructions.md

@@ -23,7 +23,7 @@ see the [Linux instructions](linux_build_instructions.md) for some suggestions.
 
 Building the Android client on Windows or Mac is not supported and doesn't work.
 
-## Install `depot_tools`
+## Install depot\_tools
 
 Clone the `depot_tools` repository: