docs: add global arg for wrangler --cmd

Author: pi0

src/content/partials/workers/wrangler-commands/global-flags.mdx

@@ -9,4 +9,6 @@ The following global flags work on every command:
 - `--help` <Type text="boolean" />
   - Show help.
 - `--config` <Type text="string" /> (not supported by Pages)
-  - Path to `wrangler.json` or `wrangler.toml` configuration file.
+  - Path to `wrangler.json` or `wrangler.toml` configuration file.
+- `--cwd` <Type text="string" />
+  - Run as if wrangler was started in <path> instead of the current working directory.