document move/copy --fast and --force

There was documentation in 66285ca3d1,
but it was lost in the man page split.

I don't know if this --force is very useful. Considered removing it
instead..

doc/git-annex-copy.mdwn

@@ -37,12 +37,15 @@ Copies the content of files from or to another remote.
 
 * `--fast`
 
-  Avoid contacting the remote to check if it has every file when copying
+  When copying content to a remote, avoid a round trip to check if the remote
-  --to it.
+  already has content. This can be faster, but might skip copying content
+  to the remote in some cases.
 
 * `--force`
 
-  Force checking the remote for every file when copying --from it.
+  When copying content from a remote, ignore location tracking information
+  and always check if the remote has content. Can be useful if the location
+  tracking information is out of date.
 
 * `--all`
 

doc/git-annex-move.mdwn

@@ -53,6 +53,18 @@ Moves the content of files from or to another remote.
 
   Use this option to move a specified key.
 
+* `--fast`
+
+  When moving content to a remote, avoid a round trip to check if the remote
+  already has content. This can be faster, but might skip moving content
+  to the remote in some cases.
+
+* `--force`
+
+  When moving content from a remote, ignore location tracking information
+  and always check if the remote has content. Can be useful if the location
+  tracking information is out of date.
+
 * file matching options
 
   The [[git-annex-matching-options]](1)