[DOC] Fix link in ErrorHighlight

Author: BurdetteLamar

lib/error_highlight/base.rb

@@ -28,7 +28,7 @@ module ErrorHighlight
   # Currently, ErrorHighlight.spot only supports a single-line code fragment.
   # Therefore, if the return value is not nil, first_lineno and last_lineno will have
   # the same value. If the relevant code fragment spans multiple lines
-  # (e.g., Array#[] of +ary[(newline)expr(newline)]+), the method will return nil.
+  # (e.g., Array#[] of <tt>ary[(newline)expr(newline)]</tt>), the method will return nil.
   # This restriction may be removed in the future.
   def self.spot(obj, **opts)
     case obj