Fix direnv option being named direnv and not load_direnv in the docs (#14309)

This is a quick followup to #13902 that fixes a mistake with the setting
naming in the docs, I accidentally made
Release Notes:

- N/A

docs/src/configuring-zed.md

@@ -193,11 +193,11 @@ left and right padding of the central pane from the workspace when the centered
 ## Direnv Integration
 
 - Description: Settings for [direnv](https://direnv.net/) integration. Requires `direnv` to be installed. `direnv` integration currently only means that the environment variables set by a `direnv` configuration can be used to detect some language servers in `$PATH` instead of installing them.
-- Setting: `direnv`
+- Setting: `load_direnv`
 - Default:
 
 ```json
-"direnv": "shell_hook"
+"load_direnv": "shell_hook"
 ```
 
 **Options**