fix quick-edit link (#1441)

Author: tshepang

book.toml

@@ -15,7 +15,7 @@ command = "mdbook-mermaid"
 
 [output.html]
 git-repository-url = "https://github.com/rust-lang/rustc-dev-guide"
-edit-url-template = "https://github.com/rust-lang/rustc-dev-guide/tree/master/{path}?mode=edit"
+edit-url-template = "https://github.com/rust-lang/rustc-dev-guide/edit/master/{path}"
 additional-js = ["mermaid.min.js", "mermaid-init.js"]
 
 [output.html.fold]