Show --editable on the uv add CLI (#6608)

## Summary

`false` is the default, so like other booleans, we should show the
non-default.

docs/reference/cli.md

@@ -515,6 +515,8 @@ uv add [OPTIONS] <PACKAGES|--requirements <REQUIREMENTS>>
 
 </dd><dt><code>--dev</code></dt><dd><p>Add the requirements as development dependencies</p>
 
+</dd><dt><code>--editable</code></dt><dd><p>Add the requirements as editable</p>
+
 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>
 
 <p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>
@@ -626,8 +628,6 @@ uv add [OPTIONS] <PACKAGES|--requirements <REQUIREMENTS>>
 
 <p>Normally, configuration files are discovered in the current directory, parent directories, or user configuration directories.</p>
 
-</dd><dt><code>--no-editable</code></dt><dd><p>Don&#8217;t add the requirements as editables</p>
-
 </dd><dt><code>--no-index</code></dt><dd><p>Ignore the registry index (e.g., PyPI), instead relying on direct URL dependencies and those provided via <code>--find-links</code></p>
 
 </dd><dt><code>--no-progress</code></dt><dd><p>Hide all progress outputs.</p>