Updated Github pages deploy script.

Signed-off-by: Sebastian Haas <sebastian@haas.tech>

bin/publish_gh_page.sh

@@ -1,5 +1,10 @@
 #!/bin/bash
 
+# Add Github deploy key for opensheetmusicdisplay/opensheetmusicdisplay.github.io.git
+echo $GH_PAGES_DEPLOY_KEY > privatedeploykey
+chmod 400 ./privatedeploykey
+ssh-add ./privatedeploykey
+
 # Prepare files to be published
 grunt docs
 grunt build:demo