update readme

Author: brotzeit

README.md

@@ -18,6 +18,7 @@
         - [Running / testing / compiling code](#running--testing--compiling-code)
         - [Clippy](#clippy)
         - [Easy insertion of dbg!](#easy-insertion-of-dbg)
+        - [More commands](#more-commands)
     - [LSP](#lsp)
         - [eglot](#eglot)
         - [lsp-mode](#lsp-mode)
@@ -154,6 +155,10 @@ program.
 
 This is bound to <kbd>C-c C-d</kbd> by default.
 
+### More commands
+
+- `rustic-toggle-mutability` toggle mut for var defined at current line
+
 ## LSP
 
 ### eglot