docs: add protocol docs and allow docx in docs/protocols

.gitignore

@@ -10,7 +10,7 @@ admin-console/dist/
 docs/reference/小程序及后台管理软件开发资料/
 软件系统说明.docx
 *.docx
-!docs/protocols/协议简述.docx
+!docs/protocols/*.docx
 cloud/sql/
 certs/
 *.pem