Hide generated structs of tracked functions from docs via #[doc(hidden)]

Author: regexident

components/salsa-macro-rules/src/setup_tracked_fn.rs

@@ -369,6 +369,7 @@ macro_rules! setup_tracked_fn {
         // The struct needs be last in the macro expansion in order to make the tracked
         // function's ident be identified as a function, not a struct, during semantic highlighting.
         // for more details, see https://github.com/salsa-rs/salsa/pull/612.
+        #[doc(hidden)]
         #[allow(non_camel_case_types)]
         $vis struct $fn_name {
             _priv: std::convert::Infallible,