Several comments in the server codebase incorrectly had the word 'string' changed to std::string as part of SERVER-13256 (see https://github.com/mongodb/mongo/commit/f2bfd36a6f3eb7e7e2587268be3cc12636703d42 and look for changes in comments).

In many cases, the edited comment is no longer correct, because the actual argument or return value is C string, not a C++ std::string, or because the reference to 'string' in the comment was used in its generic sense (e.g. 'connection string').