PolyGerrit: Add support for erlang and puppet in highlight

Change-Id: I37bfe95ba0a392ebe1b7620d780e7affeedcb318

lib/highlightjs/building.md

@@ -30,6 +30,7 @@ languages included. Build it with the following:
           css \
           d \
           dart \
+          erb \
           go \
           haskell \
           java \
@@ -44,6 +45,7 @@ languages included. Build it with the following:
           perl \
           php \
           protobuf \
+          puppet \
           python \
           ruby \
           rust \

polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js

@@ -18,6 +18,7 @@
     'application/dart': 'dart',
     'application/json': 'json',
     'application/typescript': 'typescript',
+    'application/x-erb': 'erb',
     'text/css': 'css',
     'text/html': 'html',
     'text/javascript': 'js',
@@ -39,6 +40,7 @@
     'text/x-perl': 'perl',
     'text/x-php': 'php',
     'text/x-protobuf': 'protobuf',
+    'text/x-puppet': 'puppet',
     'text/x-python': 'python',
     'text/x-ruby': 'ruby',
     'text/x-rustsrc': 'rust',