fixed docs

Author: Shlomi Noach

doc/hooks.md

@@ -69,7 +69,7 @@ The following variables are available on all hooks:
 The following variable are available on particular hooks:
 
 - `GH_OST_COMMAND` is only available in `gh-ost-on-interactive-command`
-- `GH_OST_STATUS` and `GH_OST_ELAPSED_SECONDS` are only available in `gh-ost-on-status`
+- `GH_OST_STATUS` is only available in `gh-ost-on-status`
 
 ### Examples