README: Update TODO

Author: jonnor

README.md

@@ -64,7 +64,7 @@ Also see [./doc/braindump.md](./doc/braindump.md)
 
 * Implement diffing of graph properties
 * Implement basic grouping/heuristics/context to make the diff easier to understand
-* Add basic tests for textual diffing
+* Fix inconsistencies in casing for port names
 
 ### Later