Simplify docsrs feature usage

- Don't instruct docs.rs to set it, it does so by default now:
  rust-lang/docs.rs#2390
- Because of that, check-cfg also recognizes it and does not need
  extra configuration either.

Author: jplatte

Cargo.toml

@@ -13,7 +13,6 @@ rust-version = { workspace = true }
 
 [package.metadata.docs.rs]
 all-features = true
-rustdoc-args = ["--cfg", "docsrs"]
 
 [features]
 client-api = ["dep:as_variant", "dep:ruma-client-api"]

build.rs

@@ -3,8 +3,6 @@ use std::{env, process};
 fn main() {
     // Prevent unnecessary rerunning of this build script
     println!("cargo:rerun-if-changed=build.rs");
-    // Prevent nightly CI from erroring on docsrs attributes
-    println!("cargo:rustc-check-cfg=cfg(docsrs)");
 
     let tls_features = [
         ("tls-native", env::var_os("CARGO_FEATURE_TLS_NATIVE").is_some()),