fix: adjust package name

Author: saitho

example/README.md

@@ -0,0 +1,5 @@
+```shell
+git submodule add https://github.com/getstackhead/pluginlib
+
+protoc --go_out=. --go_opt=paths=source_relative --go-grpc_out=. --go-grpc_opt=paths=source_relative pluginlib/stackhead.proto
+```

stackhead.proto

@@ -1,8 +1,8 @@
 syntax = "proto3";
 
-option go_package = "github.com/getstackhead/pluginlib/gen";
+option go_package = "github.com/getstackhead/pluginlib";
 option java_multiple_files = true;
-option java_package = "io.stackhead.pluginlib.gen";
+option java_package = "io.stackhead.pluginlib";
 option java_outer_classname = "pluginlib";
 
 package pluginlib;