depends, doc: List packages required to build qt package separately

Additionally, the `cmake` has been removed from the required packages,
as it is no longer specific to depends.

depends/README.md

@@ -41,7 +41,13 @@ The paths are automatically configured and no other options are needed.
 
 #### Common
 
-    apt install bison cmake curl make patch pkg-config python3 xz-utils
+    apt install curl make patch
+
+#### GUI
+
+Skip the following packages if you don't intend to use the GUI and will build with [`NO_QT=1`](#dependency-options):
+
+    apt install bison pkg-config python3 xz-utils
 
 #### For macOS cross compilation