chore(rust-doc): Add new Make command for CI builds (vectordotdev#18444)

* feat: no deps on rust-doc

* feat: add new ci build command and comments

rust-doc/Makefile

@@ -1,3 +1,8 @@
+# Full docs build with all dependencies for local development
 docs:
 	../scripts/environment/install-protoc.sh ${HOME}/protoc
 	PATH=${PATH}:${HOME}/protoc/ cargo doc --no-default-features --features="docs"
+# rust-doc.vector.dev specific build without the extra dependencies
+ci-docs-build:
+	../scripts/environment/install-protoc.sh ${HOME}/protoc
+	PATH=${PATH}:${HOME}/protoc/ cargo doc --no-default-features --features="docs" --no-deps