docs: Fix README TOC formatting
Fixed incorrect indentation for the README's table of contents.
Also, sorted alphabetically.
Fixes
* [Raising issues](#raising-issues)
* [Kata Containers repositories](#kata-containers-repositories)
-* [Community](#community)
* [Code Repositories](#code-repositories)
* [Kata Containers-developed components](#kata-containers-developed-components)
* [Agent](#agent)
* [Additional](#additional)
* [Hypervisor](#hypervisor)
* [Kernel](#kernel)
+ * [Community](#community)
+ * [Documentation](#documentation)
+ * [Test code](#test-code)
* [Utilities](#utilities)
* [O/S builder](#o/s-builder)
-* [Test code](#test-code)
-* [Documentation](#documentation)
* [Web content](#web-content)
---
