Update quickstart.rst

Corrected PDK variable for gf180
diff --git a/docs/source/quickstart.rst b/docs/source/quickstart.rst
index 6a5c292..f8a9b73 100644
--- a/docs/source/quickstart.rst
+++ b/docs/source/quickstart.rst
@@ -57,10 +57,12 @@
 	export PDK_ROOT=$(pwd)/dependencies/pdks # you need to export this whenever you start a new shell
 
 	# export the PDK variant depending on your shuttle, if you don't know leave it to the default
+	
+	# for sky130 MPW shuttles....
 	export PDK=sky130B
 
-    # for the GFMPW shuttles...
-	export PDK=gf180mcu
+    	# for the GFMPW shuttles...
+	export PDK=gf180mcuC
 
         make setup