* error.c: [DOC] fix Exception#backtrace_locations indent. [ci skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53582 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

error.c

@@ -868,7 +868,7 @@ exc_backtrace(VALUE exc)
  *
  *  Returns any backtrace associated with the exception. This method is
  *  similar to Exception#backtrace, but the backtrace is an array of
- *   Thread::Backtrace::Location.
+ *  Thread::Backtrace::Location.
  *
  *  Now, this method is not affected by Exception#set_backtrace().
  */