Introduce BUILD.md (#137)

Our build instructions were scattered across a few README's.

This consolidates all instructions relevant to Conduit development into
a single BUILD.md.

Fixes #134

Signed-off-by: Andrew Seigner <andrew@sig.gy>

tower-grpc-examples/README.md

@@ -1,3 +0,0 @@
-# Tower gRPC examples
-
-Demonstrates how to use Tower gRPC clients and servers with code generation.

tower-h2/README.md

@@ -1,12 +0,0 @@
-# tower-h2
-
-Tower `Service` abstractions for HTTP/2 and Rust.
-
-**This library is not production ready. Do not try to use it in a production
-environment or you will regret it!** This crate is still under active
-development and there has not yet been any focus on documentation (because you
-shouldn't be using it yet!).
-
-# License
-
-buoyant internal. not yet for distribution.