improve the USAGE section

README.md

@@ -29,25 +29,38 @@ WIt then looks for all PRs containing this containing this identifier and builds
 ```bash
 $ export GHSTACK_OAUTH_TOKEN='<personal access token>'
 
+$ gh-stack
+
+USAGE:
+    gh-stack <SUBCOMMAND>
+
+FLAGS:
+    -h, --help    Prints help information
+
+SUBCOMMANDS:
+    annotate      Annotate the descriptions of all PRs in a stack with metadata about all PRs in the stack
+    autorebase    Rebuild a stack based on changes to local branches and mirror these changes up to the remote
+    log           Print a list of all pull requests in a stack to STDOUT
+    rebase        Print a bash script to STDOUT that can rebase/update the stack (with a little help)
+
 # Idempotently add a markdown table summarizing the stack
 # to the description of each PR in the stack.
-$ gh-stack github 'stack-identifier'
+$ gh-stack annotate 'stack-identifier'
 
 # Same as above, but precede the markdown table with the 
 # contents of `filename.txt`.
-$ gh-stack github 'stack-identifier' filename.txt
+$ gh-stack annotate 'stack-identifier' -p filename.txt
 
 # Print a description of the stack to stdout.
 $ gh-stack log 'stack-identifier'
 
 # Automatically update the entire stack, both locally and remotely.
 # WARNING: This operation modifies local branches and force-pushes.
-$ gh-stack autorebase 'stack-identifier' /path/to/repo
+$ gh-stack autorebase 'stack-identifier' -C /path/to/repo
 
 # Emit a bash script that can update a stack in the case of conflicts.
 # WARNING: This script could potentially cause destructive behavior.
 $ gh-stack rebase 'stack-identifier'
-
 ```
   
 ## Strategy