Update 'README.md'

README.md

@@ -1,5 +1,12 @@
 # mdBook
 
+https://rust-lang.github.io/mdBook/guide/installation.html
+
+https://github.com/rust-lang/mdBook/releases
+
+
 ```
 cargo install mdbook
+cargo install --git https://github.com/rust-lang/mdBook.git mdbook
+
 ```