Re: Document DSM Registry

-     <title>Requesting Shared Memory After Startup</title>
+     <title>DSM Registry</title>

I'm -1 for renaming the section like this.  The existing title makes the
purpose clear and is symmetrical with the section above it.  I don't see a
need to expose the current implementation's name, either.

+      It supports creating named DSM segments with <function>GetNamedDSMSegment</function>,
+      named dynamic shared memory areas (DSAs) with <function>GetNamedDSA</function>,
+      and named hash tables backed by a DSA with <function>GetNamedDSHash</function>.

IMHO we should provide more details about DSAs and dshash tables.

One of the reasons I didn't add GetNamedDSA() and GetNamedDSHash() to these
docs was because there's no documentation for ShmemInitHash(), either.  Can
we add something for that, too?

-- 
nathan