Enable rustdoc-map nightly feature via .cargo/config.toml

… instead of using -Z on the command line.

.cargo/config.toml

@@ -49,4 +49,5 @@ rustflags = [
 # activate the target-applies-to-host feature.
 # Required for `target-applies-to-host` at the top to take effect.
 [unstable]
+rustdoc-map = true
 target-applies-to-host = true

xtask/src/doc.rs

@@ -23,9 +23,8 @@ impl DocTask {
         // Keep in sync with .github/workflows/docs.yml
         let mut cmd = cmd!(
             "
-            rustup run nightly cargo doc --no-deps --workspace
+            rustup run nightly cargo doc --all-features --no-deps --workspace
             --exclude ruma-macros --exclude ruma-identifiers-validation --exclude xtask
-            --all-features -Zrustdoc-map
             "
         )
         // Work around https://github.com/rust-lang/cargo/issues/10744