Merge remote-tracking branch 'origin/master' into ru/companion/stakin…

…g-iface

roadmap/implementers-guide/README.md

@@ -1,7 +1,14 @@
 # The Polkadot Parachain Host Implementers' Guide
 
 The implementers' guide is compiled from several source files with [`mdBook`](https://github.com/rust-lang/mdBook).
-To view it live, locally, from the repo root:
+
+## Hosted build
+
+This is avalible at https://paritytech.github.io/polkadot/book/
+
+## Local build
+
+To view it locally from the repo root:
 
 Ensure graphviz is installed:
 ```sh
@@ -16,3 +23,7 @@ cargo install mdbook mdbook-linkcheck mdbook-graphviz mdbook-mermaid
 mdbook serve roadmap/implementers-guide
 open http://localhost:3000
 ```
+
+## Specification
+
+See also the Polkadot specificaton [hosted](https://spec.polkadot.network/), and it's [source](https://github.com/w3f/polkadot-spec)).