docs: don't build platform docs for docsrs

Due to casts and use of platform specific crates in those modules
it's not really feasible to build docs for them.

After separating crates, thus should become way easier to navigate,
since backends information would be publicly available.

src/event.rs

@@ -657,11 +657,11 @@ pub enum DeviceEvent {
     /// **Web:** Only returns raw data, not OS accelerated, if [`CursorGrabMode::Locked`] is used
     /// and browser support is available, see
     #[cfg_attr(
-        any(web_platform, docsrs),
+        web_platform,
         doc = "[`ActiveEventLoopExtWeb::is_cursor_lock_raw()`][crate::platform::web::ActiveEventLoopExtWeb::is_cursor_lock_raw()]."
     )]
     #[cfg_attr(
-        not(any(web_platform, docsrs)),
+        not(web_platform),
         doc = "`ActiveEventLoopExtWeb::is_cursor_lock_raw()`."
     )]
     ///