Fix order and links in spec TOC

Fixes link to requirements section from spec table of contents and
places it in correct ordering relative to official certification.

Signed-off-by: hasheddan <georgedanielmangum@gmail.com>

spec.md

@@ -9,8 +9,8 @@
 - [Use Cases](#use-cases)
 - [Notational Conventions](#notational-conventions)
 - [Conformance](#conformance)
-	- [Minimum Requirements](#minimum-requirements)
 	- [Official Certification](#official-certification)
+	- [Requirements](#requirements)
 	- [Workflow Categories](#workflow-categories)
 		1. [Pull](#pull)
 		2. [Push](#push)