Update README.md

README.md

@@ -17,6 +17,10 @@ Supported shells:
 
 A major part of the completers has been generated from help pages so there will be some quirks here and there. Also completion depends on what [rsteube/carapace](https://github.com/rsteube/carapace) is capable of so far which by itself is limited by [spf13/pflag](https://github.com/spf13/pflag/) (e.g. shorthand-only flags are currently only possible due to [PR 256](https://github.com/spf13/pflag/pull/256)).
 
+Notable shortcomings:
+- no support for long shorthands (e.g. `-ldflags`)
+- no support for combined shorthands (e.g. `tar -xzvf`)
+
 ## Example
 
 ```