Update 'README.md'

README.md

@@ -47,6 +47,8 @@ The manifest file would do several important things:
     * recurses under current directory and writes out an `index.mf`
 * `mfer check` / `mfer check .`
     * verifies checksums of all files in manifest, displaying error and exiting nonzero if any files are missing or corrupted
+* `mfer fetch https://example.com/stuff/`
+    * fetches `/stuff/index.mf` and downloads all files listed in manifest, optionally resuming any that already exist locally, and assures cryptographic integrity of downloaded files.
 
 # Implementation Plan