fix links and wording

specification/index.rst

@@ -40,8 +40,9 @@ The specification consists of the following parts:
 
 {{apis}}
 
-Additionally, this introduction page is a valuable resource for all Matrix developers,
-including the sections on `room versions <#room-versions>`_ and `overall architecture <#architecture>`_.
+Additionally, this introduction page contains the key baseline information required to
+understand the specific APIs, including the sections on `room versions`_
+and `overall architecture <#architecture>`_.
 
 The `Appendices <appendices.html>`_ contain supplemental information not specific to
 one of the above APIs.
@@ -132,6 +133,8 @@ To propose a change to the Matrix Spec, see the explanations at `Proposals
 for Spec Changes to Matrix <proposals>`_.
 
 
+.. _`architecture`:
+
 Architecture
 ------------
 
@@ -422,6 +425,7 @@ dedicated API.  The API is symmetrical to managing Profile data.
   Would it really be overengineered to use the same API for both profile &
   private user data, but with different ACLs?
 
+.. _`room versions`:
 
 Room Versions
 -------------