fix(docker-nginx): Output yml/yaml as text/plain (#7749)

Co-authored-by: Tim Lai <timothy.lai@gmail.com>

docker/nginx.conf

@@ -7,6 +7,10 @@ events {
 http {
   include             mime.types;
   default_type        application/octet-stream;
+  types {
+    text/plain yaml;
+    text/plain yml;
+}
 
   sendfile on;