docs: Mention editor-independent configuration
diff --git a/docs/book/src/configuration.md b/docs/book/src/configuration.md
index 3f4cb19..708eecd 100644
--- a/docs/book/src/configuration.md
+++ b/docs/book/src/configuration.md
@@ -46,6 +46,11 @@
 config-related messages. Logs should show both the JSON that
 `rust-analyzer` sees as well as the updated config.
 
+(Work in progress:) It is also possible to place configuration in a
+`rust-analyzer.toml` file. It should be located in the project root or in your
+user configuration directory (e.g. `~/.config/rust-analyzer/`). This is a work in
+progress, many configuration options aren't supported yet.
+
 This is the list of config options `rust-analyzer` supports:
 
 {{#include configuration_generated.md}}