Hack: update README

hack/README.md

@@ -3,6 +3,8 @@
 The hack/ directory holds information and tools for everyone involved in the process of creating and
 distributing Docker, specifically:
 
+## Guides
+
 If you're a *contributor* or aspiring contributor, you should read CONTRIBUTORS.md.
 
 If you're a *maintainer* or aspiring maintainer, you should read MAINTAINERS.md.
@@ -10,3 +12,13 @@ If you're a *maintainer* or aspiring maintainer, you should read MAINTAINERS.md.
 If you're a *packager* or aspiring packager, you should read PACKAGERS.md.
 
 If you're a maintainer in charge of a *release*, you should read RELEASE-CHECKLIST.md.
+
+## Roadmap
+
+A high-level roadmap is available at ROADMAP.md.
+
+
+## Build tools
+
+make.sh is the primary build tool for docker. It is used for compiling the official binary,
+running the test suite, and pushing releases.