Sync with 1.8.5.1

* maint:
  Git 1.8.5.1
  ref-iteration doc: add_submodule_odb() returns 0 for success

Documentation/RelNotes/1.8.5.1.txt

+Git v1.8.5.1 Release Notes
+==========================
+
+Fixes since v1.8.5
+------------------
+
+ * "git submodule init" copied "submodule.$name.update" settings from
+   .gitmodules to .git/config without making sure if the suggested
+   value was sensible.

Documentation/git.txt

@@ -43,9 +43,10 @@ unreleased) version of Git, that is available from 'master'
 branch of the `git.git` repository.
 Documentation for older releases are available here:
 
-* link:v1.8.5/git.html[documentation for release 1.8.5]
+* link:v1.8.5.1/git.html[documentation for release 1.8.5.1]
 
 * release notes for
+  link:RelNotes/1.8.5.1.txt[1.8.5.1],
   link:RelNotes/1.8.5.txt[1.8.5].
 
 * link:v1.8.4.5/git.html[documentation for release 1.8.4.5]

Documentation/technical/api-ref-iteration.txt

@@ -50,10 +50,10 @@ submodules object database. You can do this by a code-snippet like
 this:
 
 	const char *path = "path/to/submodule"
-	if (!add_submodule_odb(path))
+	if (add_submodule_odb(path))
 		die("Error submodule '%s' not populated.", path);
 
-`add_submodule_odb()` will return an non-zero value on success. If you
+`add_submodule_odb()` will return zero on success. If you
 do not do this you will get an error for each ref that it does not point
 to a valid object.