[DOC] Fix broken links to operator methods

Once https://github.com/ruby/rdoc/pull/865 is merged, these hacks
are no longer needed.

range.c

@@ -2168,7 +2168,7 @@ range_count(int argc, VALUE *argv, VALUE range)
  *
  * A user-defined class that is to be used in a range
  * must implement instance <tt><=></tt>;
- * see {Integer#<=>}[Integer.html#label-method-i-3C-3D-3E].
+ * see {Integer#<=>}[Integer.html#method-i-3C-3D-3E].
  * To make iteration available, it must also implement
  * instance method +succ+; see Integer#succ.
  *

string.c

@@ -4188,7 +4188,7 @@ rb_str_rindex_m(int argc, VALUE *argv, VALUE str)
  *  returned by <tt>object =~ self</tt>.
  *
  *  Note that <tt>string =~ regexp</tt> is different from <tt>regexp =~ string</tt>
- *  (see {Regexp#=~}[https://ruby-doc.org/core-2.7.1/Regexp.html#method-i-3D-7E]):
+ *  (see {Regexp#=~}[Regexp.html#method-i-3D~]):
  *
  *    number= nil
  *    "no. 9" =~ /(?<number>\d+)/