added wiki comments + wiki-generating python script

src/returns.rs

@@ -6,8 +6,22 @@ use syntax::visit::FnKind;
 
 use utils::{span_lint, snippet, match_path_ast, in_external_macro};
 
+/// **What it does:** This lint checks for return statements at the end of a block. It is `Warn` by default.
+///
+/// **Why is this bad?** Removing the `return` and semicolon will make the code more rusty.
+///
+/// **Known problems:** None
+///
+/// **Example:** `fn foo(x: usize) { return x; }`
 declare_lint!(pub NEEDLESS_RETURN, Warn,
               "using a return statement like `return expr;` where an expression would suffice");
+/// **What it does:** This lint checks for `let`-bindings, which are subsequently returned. It is `Warn` by default.
+///
+/// **Why is this bad?** It is just extraneous code. Remove it to make your code more rusty.
+///
+/// **Known problems:** None
+///
+/// **Example:** `{ let x = ..; x }`
 declare_lint!(pub LET_AND_RETURN, Warn,
               "creating a let-binding and then immediately returning it like `let x = expr; x` at \
                the end of a block");