Documentation/git-update-ref.txt: demote symlink to last section

Move the discussion of file system symbolic links to a new “Notes”
section (inspired by the one in git-symbolic-ref(1)) since this is
mostly of historical note at this point, not something that is needed in
the main section of the documentation.

Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Taylor Blau <me@ttaylorr.com>

Author: LemmingAvalanche

Documentation/git-update-ref.txt

@@ -29,14 +29,6 @@ It also allows a "ref" file to be a symbolic pointer to another
 ref file by starting with the four-byte header sequence of
 "ref:".
 
-More importantly, it allows the update of a ref file to follow
-these symbolic pointers, whether they are symlinks or these
-"regular file symbolic refs".  It follows *real* symlinks only
-if they start with "refs/": otherwise it will just try to read
-them and update them as a regular file (i.e. it will allow the
-filesystem to follow them, but will overwrite such a symlink to
-somewhere else with a regular filename).
-
 If --no-deref is given, <ref> itself is overwritten, rather than
 the result of following the symbolic pointers.
 
@@ -185,6 +177,17 @@ An update will fail (without changing <ref>) if the current user is
 unable to create a new log file, append to the existing log file
 or does not have committer information available.
 
+NOTES
+-----
+
+Symbolic refs were initially implemented using symbolic links.  This is
+now deprecated since not all filesystems support symbolic links.
+
+This command follows *real* symlinks only if they start with "refs/":
+otherwise it will just try to read them and update them as a regular
+file (i.e. it will allow the filesystem to follow them, but will
+overwrite such a symlink to somewhere else with a regular filename).
+
 GIT
 ---
 Part of the linkgit:git[1] suite