Add troubleshooting secion

Author: matklad

docs/user/readme.adoc

@@ -98,6 +98,16 @@ You'll need Cargo, nodejs and npm for this.
 
 Note that installing via `xtask install` does not work for VS Code Remote, instead you'll need to install the `.vsix` manually.
 
+==== Troubleshooting
+
+Here are some useful self-diagnostic commands:
+
+* **Rust Analyzer: Show RA Version** shows the version of `rust-analyzer` binary
+* **Rust Analyzer: Status** prints some statistics about the server, like the few latest LSP requests
+* To enable server-side logging, run with `env RUST_LOG=info` and see `Output > Rust Analyzer Language Server` in VS Code's panel.
+* To log all LSP requests, add `"rust-analyzer.trace.server": "verbose"` to the settings and look for `Server Trace` in the panel.
+* To enable client-side logging, add `"rust-analyzer.trace.extension": true` to the settings and open the `Console` tab of VS Code developer tools.
+
 === Language Server Binary
 
 Other editors generally require `rust-analyzer` binary to be in `$PATH`.