Document new wrangler pages deployment list property --json

See cloudflare/workers-sdk#8318

Author: petebacondarwin

src/content/docs/workers/wrangler/commands.mdx

@@ -1046,6 +1046,8 @@ wrangler pages deployment list [--project-name <PROJECT_NAME>]
   - The name of the project you would like to list deployments for.
 - `--environment` <Type text="'production'|'preview'" /> <MetaInfo text="optional" />
   - Environment type to list deployments for.
+- `--json` <Type text="boolean" /> <MetaInfo text="optional" />
+  - Whether to output the list in JSON format.
 
 <Render file="wrangler-commands/global-flags" product="workers" />