Develop script does full build now if dist folder does not exist

develop

 #!/bin/bash
 
+# If dist directory doesn’t exist, clean the cache and
+# recreate it so we ensure a full build.
+if [ ! -d "dist" ]; then
+  echo "(!) dist/ directory does not exist; doing a full build"
+  mkdir dist
+  ./clean-cache
+fi
+
 # Start serving the dist directory at https://localhost as a background process.
 site dist &
 SITE_JS_PID=$!