patch 9.0.1113: users cannot easily try out a PR

Problem:    Users cannot easily try out a PR.
Solution:   Add an "artifacts" section to the AppVeyor CI config. (Christian
            Brabandt, closes #11762)

.appveyor.yml

@@ -29,4 +29,10 @@ test_script:
     # Testing with MSVC console version
   - nmake -f Make_mvc.mak VIMPROG=..\vim
 
+artifacts:
+  - path: src/vim.exe
+    name: vim
+  - path: src/gvim.exe
+    name: gvim
+
 # vim: sw=2 sts=2 et ts=8 sr