update known limitations section

Author: achristmascarl

README.md

@@ -556,8 +556,6 @@ features
 <!-- TOC --><a name="known-issues-and-limitations"></a>
 ## known issues and limitations
 
-- aborting a running query does not cancel the process running the query on database servers
-  like postgres or mysql. follow https://github.com/achristmascarl/rainfrog/issues/178 for updates
 - geometry types are not currently supported
 - for x11 and wayland, yanking does not copy to the system clipboard, only
   to the query editor's buffer. see <https://github.com/achristmascarl/rainfrog/issues/83>