Merge pull request #4 from hackedy/stub-readme

add simple README

README.md

@@ -0,0 +1,37 @@
+# P4PP
+
+p4pp is a standards-compliant preprocessor for the [P4 Language](https://p4.org)
+language.
+
+## Installing from source
+1. Check the installed version of OCaml:
+    ```
+    ocamlc -v
+    ```
+    If the version is less than 4.09.0, upgrade:
+    ```
+    opam switch 4.09.0
+    ```
+
+1. Use OPAM to build and install p4pp. 
+   ```
+   opam pin add p4pp <path to root of p4pp repo>
+   ```
+
+## Running p4pp
+
+TODO
+
+## Contributing
+
+p4pp is an open-source project. We encourage contributions!
+Please file issues on
+[Github](https://github.com/cornell-netlab/p4pp/issues).
+
+## Credits
+
+p4pp was written by Nate Foster.
+
+## License
+
+p4pp is released under the [Apache2 License](LICENSE).