tests: Add postive test group to validatelayerdoc script

Change-Id: If8b1d81d4c755ba8fc409d141387291d0e7d813d
diff --git a/vk_layer_documentation_generate.py b/vk_layer_documentation_generate.py
index f87091d..7086fb6 100755
--- a/vk_layer_documentation_generate.py
+++ b/vk_layer_documentation_generate.py
@@ -133,7 +133,7 @@
 
 # Class to parse the validation layer test source and store testnames
 class TestParser:
-    def __init__(self, test_file_list, test_group_name=['VkLayerTest', 'VkWsiEnabledLayerTest']):
+    def __init__(self, test_file_list, test_group_name=['VkLayerTest', 'VkPositiveLayerTest', 'VkWsiEnabledLayerTest']):
         self.test_files = test_file_list
         self.tests_set = set()
         self.test_trigger_txt_list = []