Add Picapad custom favicon

pica-etherpad/entrypoint.sh

@@ -85,6 +85,7 @@ cat <<- EOF > /opt/etherpad-lite/settings.json
   "skinName": "${ETHERPAD_THEME}",
   "defaultPadText": "${ETHERPAD_DEFAULT_TEXT}",
   "abiword" : "/usr/bin/abiword",
+  "favicon": "favicon.ico"
 EOF
 
 if [ $ETHERPAD_ADMIN_PASSWORD ]; then