fix title conflict in arch docs

active/os_arch/arch-base.md

@@ -11,9 +11,9 @@ instructions for building a:
 
 - [Arch Base](#arch-base)
   - [Table of Contents](#table-of-contents)
-  - [Installation](#installation)
+  - [Installing Arch](#installing-arch)
     - [Preparation](#preparation)
-    - [Installation](#installation-1)
+    - [Installation](#installation)
   - [Post Install](#post-install)
     - [Backup (or restore)](#backup-or-restore)
     - [Base Tools](#base-tools)
@@ -58,7 +58,7 @@ instructions for building a:
     - [VLAN Setup](#vlan-setup)
   - [Date and Time](#date-and-time)
 
-## Installation
+## Installing Arch
 
 ### Preparation