Add new API endpoint & explicit type parameter

See https://github.com/w3c/spec-generator/wiki/Migrating-Bikeshed-HTTP-API-usage-to-spec%E2%80%90generator

Author: theIDinside

Makefile

@@ -2,7 +2,7 @@ LOCAL_BIKESHED := $(shell command -v bikeshed 2> /dev/null)
 
 index.html: index.bs
 ifndef LOCAL_BIKESHED
-	curl https://api.csswg.org/bikeshed/ -f -F file=@$< >$@;
+	curl https://www.w3.org/publications/spec-generator/ -f -F type=bikeshed-spec -F file=@$< >$@;
 else
 	bikeshed spec $<
 endif