Add --cname option to CI for ghp-import

rust-embedded/wg#208

Signed-off-by: Nick Stevens <nick.stevens@smartthings.com>

Author: nastevens

ci/after-success.sh

@@ -5,7 +5,7 @@ main() {
     curl -Ls https://github.com/davisp/ghp-import/archive/master.tar.gz |
         tar --strip-components 1 -C ghp-import -xz
 
-    ./ghp-import/ghp_import.py doc
+    ./ghp-import/ghp_import.py --cname=docs.rust-embedded.org doc
 
     # NOTE(+x) don't print $GH_TOKEN to the console!
     set +x