Update client_max_body_size for managed APIs (#327)

diff --git a/conf.d/managed_endpoints.conf b/conf.d/managed_endpoints.conf
index 09613cc..7df79a4 100644
--- a/conf.d/managed_endpoints.conf
+++ b/conf.d/managed_endpoints.conf
@@ -72,6 +72,7 @@
         set $responseBody '';
 
         proxy_read_timeout 70s;
+        client_max_body_size 5m;
 
         access_by_lua_block {
             local routing = require "routing"