Add protoc-gen-xo to global extension registry (#9997)

diff --git a/docs/options.md b/docs/options.md
index bda41c2..8c22af1 100644
--- a/docs/options.md
+++ b/docs/options.md
@@ -324,3 +324,7 @@
 1. Protonium
    * Website: https://github.com/zyp/protonium
    * Extension: 1146
+
+1. Protoc-gen-xo
+   * Website: https://github.com/xo/ecosystem
+   * Extension: 1147