feat: requirements && how to build

README.md

@@ -1,5 +1,35 @@
 # The Pillars of Programming
 
+## Requirements
+
+Building the book requires [mdBook], ideally the same version that
+rust-lang/rust uses in [this file][rust-mdbook]. To get it:
+
+[mdBook]: https://github.com/rust-lang/mdBook
+[rust-mdbook]: https://github.com/rust-lang/rust/blob/master/src/tools/rustbook/Cargo.toml
+
+```bash
+$ cargo install mdbook --locked --version <version_num>
+```
+
+The book also uses two mdbook plugins which are part of this repository. If you
+do not install them, you will see warnings when building and the output will not
+look right, but you *will* still be able to build the book. To use the plugins,
+you should run:
+
+```bash
+$ cargo install --locked --path packages/mdbook-trpl-listing
+$ cargo install --locked --path packages/mdbook-trpl-note
+```
+
+## Building
+
+To build the book, type:
+
+```bash
+$ mdbook build
+```
+
 ### Authored by
 
 * @misterclayt0n