readme: fix asap7 liberty files path

Author: magancarz

README.md

@@ -264,7 +264,7 @@ For liberty files paths simplicity, you can export the path to their directory a
 
 <!-- name="export-liberty-path" -->
 ```
-export LIB_DIR=$(pwd)/OpenROAD-flow-scripts/flow/platforms/asap7/lib/
+export LIB_DIR=$(pwd)/OpenROAD-flow-scripts/flow/platforms/asap7/lib/NLDM/
 ```
 
 Go to the synthesis results directory and then run the glitch power script: