Fix typo.

Match "build-rust-analyzer" in src/building/how-to-build-and-run.md and in the default editor settings from the rustc repo.

Author: Ozzy1423

src/building/suggested.md

@@ -97,7 +97,7 @@ for two reasons:
   additional rebuilds in some cases.
 
 To avoid these problems:
-- Add `--build-dir=build/rust-analyzer` to all of the custom `x` commands in
+- Add `--build-dir=build-rust-analyzer` to all of the custom `x` commands in
   your editor's rust-analyzer configuration.
   (Feel free to choose a different directory name if desired.)
 - Modify the `rust-analyzer.rustfmt.overrideCommand` setting so that it points