Draft: improve the README files with links

src/Mod/Draft/drafttests/README.md

@@ -0,0 +1,23 @@
+2020 February
+
+These files provide the unit tests classes based on the standard Python
+`unittest` module.
+
+These files should be imported from the main `TestDraft.py` module
+which is the one registered in the program in `InitGui.py`.
+
+Each module should define a class derived from `unittest.TestCase`,
+and the individual methods of the class correspond to the individual
+unit tests which try a specific function in the workbench.
+
+The tests should be callable from the terminal.
+```
+program -t TestDraft  # all tests
+program -t drafttests.test_creation  # only creation functions
+
+# A specific test
+program -t drafttests.test_creation.DraftCreation.test_line
+```
+
+For more information see the thread:
+[New unit tests for Draft Workbench](https://forum.freecadweb.org/viewtopic.php?f=23&t=40405)