add prometheus and protobuf as submodules

.gitmodules

@@ -0,0 +1,6 @@
+[submodule "prometheus"]
+	path = prometheus
+	url = git@github.com:prometheus/prometheus.git
+[submodule "protobuf"]
+	path = protobuf
+	url = https://github.com/gogo/protobuf.git

app/src/project/core/prometheus_protobuf/README.md

@@ -1,6 +1,6 @@
 These files were created by:
 
-1. cloning prometheus (git@github.com:prometheus/prometheus.git) and protobuf (git clone https://github.com/gogo/protobuf.git)
+1. checking out submodules of this repository (prometheus and protobuf)
 2. Installing go and a bunch of stuff I'm not sure is necessary
 3. Running `make proto` in prometheus's root dir until the error was `--gogofast_out: protoc-gen-gogofast: Plugin failed with status code 1.` - not sure if that was necessary
 4. running `protoc -I=. -I=../../protobuf --python_out=. ../../protobuf/gogoproto/gogo.proto types.proto remote.proto` in `prometheus/prompb`