Fix compatable typo (yet to add to codespell)

=== Do not change lines below ===
{
 "chain": [],
 "cmd": "git-sedi compatable compatible",
 "exit": 0,
 "extra_inputs": [],
 "inputs": [],
 "outputs": [],
 "pwd": "."
}
^^^ Do not change lines above ^^^

doc/todo/generic_readonly_http_remote/comment_2_c81b458a8ee0f15950adbd32dd168972._comment

@@ -17,7 +17,7 @@ that almost everything uses. But in its favor:
 
 * --sameas already relies on special remotes using the same path form, and so
   it seems we're going to end up documenting which special remotes are
-  compatable. That information could even be encoded in the remotes and
+  compatible. That information could even be encoded in the remotes and
   git-annex sanity check uses of --sameas. 
 
   Perhaps --sameas is a slippery slope and this should not continue down it,