Remove doc.go

Summary:
1. Reduce file clutter. Having a separate `doc.go` file is unnecessary - just an additional file to take up space.
2. `doc.go` is not idiomatic. Go recommends putting package level comment in one of the source files, right before `package` statement: https://tip.golang.org/doc/comment#package
3. `doc.go` was not even included into `thrift_library` build - so users were not even getting access to the package level comment: https://www.internalfb.com/code/fbsource/[2b32460319ab]/tools/build_defs/fbcode_macros/build_defs/lib/thrift/go.bzl?lines=49-54

This diff removes `doc.go` and move the package level comment into `svcs.go` (right before `package` statement - as recommended by Go style guide).

Reviewed By: podtserkovskiy

Differential Revision: D79910278

fbshipit-source-id: ebffddf6f867573013ac02aaa7ccebec32140d8d

Author: echistyakov

third-party/thrift/src/thrift/compiler/generate/t_mstch_go_generator.cc

@@ -856,9 +856,6 @@ void t_mstch_go_generator::generate_program() {
   if (data_.gen_metadata) {
     render_to_file(prog, "metadata.go", "metadata.go");
   }
-  if (program->has_doc()) {
-    render_to_file(prog, "doc.go", "doc.go");
-  }
 }
 
 void t_mstch_go_generator::set_mstch_factories() {

third-party/thrift/src/thrift/compiler/generate/templates/go/doc.go.mustache

@@ -16,6 +16,9 @@
 }}
 {{> common/auto_generated_go}}
 
+{{#program:docs?}}
+{{program:docs}}
+{{/program:docs?}}
 package {{program:go_pkg_name}}
 
 import (

third-party/thrift/src/thrift/compiler/generate/templates/go/svcs.go.mustache

@@ -87,8 +87,8 @@ class ServiceHandler<::cpp2::C> : public apache::thrift::ServerInterface {
 namespace detail {
 template <> struct TSchemaAssociation<::cpp2::C, false> {
   static ::folly::Range<const ::std::string_view*>(*bundle)();
-  static constexpr int64_t programId = -2642339036077964808;
-  static constexpr ::std::string_view definitionKey = {"\x17\x8c\x04\xf5\x38\x9f\xfe\xa5\x44\x93\x1e\xe9\xca\x4c\xa8\xa7", 16};
+  static constexpr int64_t programId = -8518854100704916787;
+  static constexpr ::std::string_view definitionKey = {"\x3f\x6e\x14\x31\x82\xa7\x8d\xe4\xd6\xd5\x06\xf6\xf9\x4e\x9c\xbf", 16};
 };
 }
 } // namespace apache::thrift