[ruby/date] Fixed markups for bold [ci skip]

https://github.com/ruby/date/commit/404f9d2096

ext/date/date_core.c

@@ -4353,7 +4353,7 @@ date_s__parse_internal(int argc, VALUE *argv, VALUE klass)
  * Parses the given representation of date and time, and returns a
  * hash of parsed elements.
  *
- * This method **does not** function as a validator.  If the input
+ * This method *does not* function as a validator.  If the input
  * string does not match valid formats strictly, you may get a cryptic
  * result.  Should consider to use `Date._strptime` or
  * `DateTime._strptime` instead of this method as possible.
@@ -4377,7 +4377,7 @@ date_s__parse(int argc, VALUE *argv, VALUE klass)
  * Parses the given representation of date and time, and creates a
  * date object.
  *
- * This method **does not** function as a validator.  If the input
+ * This method *does not* function as a validator.  If the input
  * string does not match valid formats strictly, you may get a cryptic
  * result.  Should consider to use `Date.strptime` instead of this
  * method as possible.
@@ -8018,7 +8018,7 @@ datetime_s_strptime(int argc, VALUE *argv, VALUE klass)
  * Parses the given representation of date and time, and creates a
  * DateTime object.
  *
- * This method **does not** function as a validator.  If the input
+ * This method *does not* function as a validator.  If the input
  * string does not match valid formats strictly, you may get a cryptic
  * result.  Should consider to use `DateTime.strptime` instead of this
  * method as possible.