Merge branch 'ab/tech-docs-to-help'

Expose a lot of "tech docs" via "git help" interface.

* ab/tech-docs-to-help:
  docs: move http-protocol docs to man section 5
  docs: move cruft pack docs to gitformat-pack
  docs: move pack format docs to man section 5
  docs: move signature docs to man section 5
  docs: move index format docs to man section 5
  docs: move protocol-related docs to man section 5
  docs: move commit-graph format docs to man section 5
  git docs: add a category for file formats, protocols and interfaces
  git docs: add a category for user-facing file, repo and command UX
  git help doc: use "<doc>" instead of "<guide>"
  help.c: remove common category behavior from drop_prefix() behavior
  help.c: refactor drop_prefix() to use a "switch" statement"

Documentation/config/lsrefs.txt

@@ -1,7 +1,7 @@
 lsrefs.unborn::
 	May be "advertise" (the default), "allow", or "ignore". If "advertise",
 	the server will respond to the client sending "unborn" (as described in
-	protocol-v2.txt) and will advertise support for this feature during the
+	linkgit:gitprotocol-v2[5]) and will advertise support for this feature during the
 	protocol v2 capability advertisement. "allow" is the same as
 	"advertise" except that the server will not advertise support for this
 	feature; this is useful for load-balanced servers that cannot be

Documentation/config/pack.txt

@@ -166,7 +166,7 @@ permuted into their appropriate location when writing a new bitmap.
 
 pack.writeReverseIndex::
 	When true, git will write a corresponding .rev file (see:
-	link:../technical/pack-format.html[Documentation/technical/pack-format.txt])
+	linkgit:gitformat-pack[5])
 	for each new packfile that it writes in all places except for
 	linkgit:git-fast-import[1] and in the bulk checkin mechanism.
 	Defaults to false.

Documentation/config/protocol.txt

@@ -58,6 +58,6 @@ protocol.version::
 * `1` - the original wire protocol with the addition of a version string
   in the initial response from the server.
 
-* `2` - link:technical/protocol-v2.html[wire protocol version 2].
+* `2` - Wire protocol version 2, see linkgit:gitprotocol-v2[5].
 
 --