Docs: add TOC to user-guide/configuring.md (#13727)

* Docs: add TOC to user-guide/configuring.md

* change bullets from - to *

* add empty line between heading & list

* Docs: correct TOC link in docs/user-guide/configuring.md

Co-authored-by: Milos Djermanovic <milos.djermanovic@gmail.com>

Co-authored-by: Milos Djermanovic <milos.djermanovic@gmail.com>

docs/user-guide/configuring.md

@@ -13,6 +13,27 @@ There are several pieces of information that can be configured:
 
 All of these options give you fine-grained control over how ESLint treats your code.
 
+## Table of Contents
+
+* [Specifying Parser Options](#specifying-parser-options)
+* [Specifying Parser](#specifying-parser)
+* [Specifying Processor](#specifying-processor)
+* [Specifying Environments](#specifying-environments)
+* [Specifying Globals](#specifying-globals)
+* [Configuring Plugins](#configuring-plugins)
+* [Configuring Rules](#configuring-rules)
+* [Disabling Rules with Inline Comments](#disabling-rules-with-inline-comments)
+* [Configuring Inline Comment Behaviors](#configuring-inline-comment-behaviors)
+* [Adding Shared Settings](#adding-shared-settings)
+* [Using Configuration Files](#using-configuration-files-1)
+* [Configuration File Formats](#configuration-file-formats)
+* [Configuration Cascading and Hierarchy](#configuration-cascading-and-hierarchy)
+* [Extending Configuration Files](#extending-configuration-files)
+* [Configuration Based on Glob Patterns](#configuration-based-on-glob-patterns)
+* [Comments in Configuration Files](#comments-in-configuration-files)
+* [Ignoring Files and Directories](#ignoring-files-and-directories)
+* [Personal Configuration File (deprecated)](#personal-configuration-file-deprecated)
+
 ## Specifying Parser Options
 
 ESLint allows you to specify the JavaScript language options you want to support. By default, ESLint expects ECMAScript 5 syntax. You can override that setting to enable support for other ECMAScript versions as well as JSX by using parser options.