Update README.md
diff --git a/README.md b/README.md
index bd712d8..0049660 100644
--- a/README.md
+++ b/README.md
@@ -43,6 +43,7 @@
     - uses either openroad or standalone opensta binary
 - `timing_top.tcl` 
     - runs opensta performing sta on the caravel (top) level
+    - loads top level `sdc` which in the case of this repo is [caravel.sdc](./caravel/sdc/caravel.sdc)
     - uses openroad binary
 
 #### settings or env