Integrate the markdown book into the codebase

This implies that the book should describe exactly what is implemented,
and will not lead the way and eventually bitrot as the RFCs do.

README.md

@@ -295,6 +295,34 @@ $ git clone https://github.com/solana-labs/solana.git
 $ cd solana
 ```
 
+Building the Solana book
+---
+
+Install mdbook:
+
+```bash
+cargo install mdbook
+```
+
+Run any Rust tests in the markdown:
+
+```bash
+mdbook test
+```
+
+Render markdown as HTML:
+
+```bash
+mdbook build
+```
+
+Render and view the book:
+
+```bash
+mdbook build --open
+```
+
+
 Testing
 ---
 
@@ -443,3 +471,4 @@ better way to solve the same problem, a Pull Request with your solution would mo
 welcome! Likewise, if rewriting a test can better communicate what code it's protecting, please
 send us that patch!
 
+