Merge #276

276: book.toml: add link to GitHub repo r=adamgreig a=MarcoIeni

This will show a GitHub icon in the website that links to the repo

Co-authored-by: Marco Ieni <[email protected]>

Author: bors[bot]

book.toml

@@ -3,3 +3,6 @@ authors = ["James Munns"]
 multilingual = false
 src = "src"
 title = "The Embedded Rust Book"
+
+[output.html]
+git-repository-url = "https://github.com/rust-embedded/book"