Update for mdbook

Update URL to point to the manual directly (rather than getting
redirected), and remove old references to .adoc files.

Author: Wilfred

README.md

@@ -1,7 +1,5 @@
 # rust-analyzer.github.io
 
-[![Build Status](https://travis-ci.org/rust-analyzer/rust-analyzer.github.io.svg?branch=src)](https://travis-ci.org/rust-analyzer/rust-analyzer.github.io)
-
 Website for rust-analyzer. To report bugs in rust-analyzer itself, see https://github.com/rust-analyzer/rust-analyzer.
 
 ## Building
@@ -10,7 +8,3 @@ Website for rust-analyzer. To report bugs in rust-analyzer itself, see https://g
 $ bundle --path=.bundle/gems
 $ bundle exec jekyll serve
 ```
-
-The markup language we use (.adoc) is AsciiDoctor. It is awesome :-).
-
-[AsciiDoctor Syntax Quick Reference](https://asciidoctor.org/docs/asciidoc-syntax-quick-reference/).