Added suport for bash auto-complete and config options for downloading burrow from the repo

README.md

@@ -46,9 +46,13 @@ The following environment variables are supported:
    but you should use something else for a customized version.  Export files
    in stages may add suffixes to `IMG_NAME`.
 
- * `RUDEFOX_BURROW_VERSION` (Default: `0.0.2`)
+ * `RUDEFOX_REPO_USERNAME` (Default: `anonymous`)
 
-   The version of Rudefox Burrow to download and install.
+   If the value is set to `anonymous`, then Burrow is pulled from the publicly available Rudefox repository.  Otherwise, the build attempts to login to the Rudefox private repository for access to SNAPSHOT builds using the provided `RUDEFOX_REPO_USERNAME` / `RUDEFOX_REPO_PASSWORD` credentials.
+
+ * `RUDEFOX_BURROW_VERSION` (Default: `latest`)
+
+   If the value is set to `latest`, then the latest version is pulled from the Rudefox repository and installed.  Otherwise, the specified version is downloadedand installed.
 
  * `RELEASE` (Default: buster)