documentation for making git add only annex when configured by annex.largefiles

Code change should be trvial, but not yet implemented. This
significantly complicated the task of documenting how git-annex works.

I'm not sure how useful the annex.gitaddtoannex confguration is after
this change; seems that if a user has an annex.largefiles they will want
it applied consistently. But the last thing I want to hear is more
complaining from users about git add doing something they don't want it
to.

There's a pretty high risk users who got used to the git add behavior
and don't have annex.largefiles configured will miss the NEWS and
complain bitterly about their suddenly bloated repositories. Oh well.

Removed outdated comments about the old behavior to avoid confusion.
I don't know if I've found all the places that griping spread to.

doc/tips/unlocked_files.mdwn

@@ -14,41 +14,45 @@ They are stored in the git repository differently, and they appear as
 regular files in the working tree, instead of the symbolic links used for
 locked files.
 
-## adding unlocked files
+## using unlocked files
 
-Instead of using `git annex add`, use `git add`, and the file will be
-stored in git-annex, but left unlocked.
+You can unlock any annexed file:
 
-[[!template id=note text="""
-Want `git add` to add some file contents to the annex, but store the contents of
-smaller files in git itself? Configure annex.largefiles to match the former.
-See [[largefiles]].
-"""]]
+	# git annex unlock my_cool_big_file
 
-	# cp ~/my_cool_big_file .
-	# git add my_cool_big_file
-	# git commit -m "added my_cool_big_file to the annex"
-	[master (root-commit) 92f2725] added my_cool_big_file to the annex
-	 1 file changed, 1 insertion(+)
-	  create mode 100644 my_cool_big_file
-	# git annex find
-	my_cool_big_file
+That changes what's stored in git between a git-annex symlink
+(locked) and a git-annex pointer file (unlocked). You can commit
+the change, if you want that file to be unlocked in other clones of the
+repository. To lock the file again, use `git annex lock`.
 
-You can make whatever modifications you want to unlocked files, and commit
-your changes.
+The nice thing about an unlocked file is that you can modify it
+in place -- it's a regular file. And you can commit your changes.
 
 	# echo more stuff >> my_cool_big_file
-	# git mv my_cool_big_file my_cool_bigger_file
 	# git commit -a -m "some changes"
 	[master 196c0e2] some changes
-	 2 files changed, 1 insertion(+), 1 deletion(-)
-	 delete mode 100644 my_cool_big_file
-	 create mode 100644 my_cool_bigger_file
+	 1 files changed, 1 insertion(+), 1 deletion(-)
 
-Under the hood, this uses git's [[todo/smudge]] filter interface, and
-git-annex converts between the content of the big file and a pointer file,
-which is what gets committed to git. All the regular git-annex commands
-(get, drop, etc) can be used on unlocked files too.
+Notice that `git commit -a` added the new content of the file to the annex,
+and only committed a change to the pointer. That happened because git-annex
+knows this was an annexed file before. Git leaves the file unlocked, so
+you can continue to make modifications to it.
+
+By default, using git to add a file that has not been annexed before will
+still add its contents to git, not to the annex. If you tell git-annex what
+files are large, it will arrange for the large files to be added to the
+annex, and the small ones to be added to git. This is done by configuring
+annex.largefiles. See [[largefiles]] for full documentation of that.
+
+All the regular git-annex commands (find, get, drop, etc) can be used on
+unlocked files as well as locked files. When you drop the content of
+an unlocked file, it will be replaced by a pointer file, which
+looks like "/annex/objects/...". So if you open a file and see
+that, you'll need to use `git annex get`.
+
+Under the hood, unlocked files use git's [[todo/smudge]] filter interface,
+and git-annex converts between the content of the big file and a pointer
+file, which is what gets committed to git.
 
 [[!template id=note text="""
 By default, git-annex commands will add files in locked mode,
@@ -57,14 +61,7 @@ mode is used. To make them always use unlocked mode, run:
 `git config annex.addunlocked true`
 """]]
 
-## mixing locked and unlocked files
-
-A repository can contain both locked and unlocked files. You can switch 
-a file back and forth using the `git annex lock` and `git annex unlock`
-commands. This changes what's stored in git between a git-annex symlink
-(locked) and a git-annex pointer file (unlocked). To add a file to
-the repository in locked mode, use `git annex add`; to add a file in
-unlocked mode, use `git add`.
+## adjusted branches
 
 If you want to mostly keep files locked, but be able to locally switch
 to having them all unlocked, you can do so using `git annex adjust
@@ -73,6 +70,15 @@ useful when using filesystems like FAT, and OS's like Windows that don't
 support symlinks. Indeed, `git-annex init` detects such filesystems and
 automatically sets up a repository to use all unlocked files.
 
+## finding unlocked files
+
+While it's easy to see when a file is a git-annex symlink, unlocked files
+look the same as files stored in git. To see what files are unlocked or
+locked, many git-annex commands support `--unlocked` and `--locked`
+options.
+
+	git annex find --unlocked
+
 ## imperfections
 
 Unlocked files mostly work very well, but there are a