Add direnv allow to initial steps

Author: urob

readme.md

@@ -320,6 +320,9 @@ environment is _completely isolated_ and won't pollute your system.
    # This takes a while when entering the workspace for the first time.
    cd zmk-workspace
 
+   # Enable direnv for the workspace
+   direnv allow
+
    # Initialize the Zephyr workspace and pull in the ZMK dependencies
    # (same as `west init -l config && west update && west zephyr-export`)
    just init