added JSON extensions for Sublime Text

Signed-off-by: Haralan Dobrev <hkdobrev@gmail.com>

lib/linguist/languages.yml

@@ -632,6 +632,14 @@ JSON:
   ace_mode: json
   searchable: false
   primary_extension: .json
+  extensions:
+  - .sublime-keymap
+  - .sublime_metrics
+  - .sublime-mousemap
+  - .sublime-project
+  - .sublime_session
+  - .sublime-settings
+  - .sublime-workspace
 
 Java:
   type: programming