Changing external link indicator

Author: VesaJuvonen

docs/toc.yml

@@ -1620,13 +1620,13 @@
     href: community/open-source-projects.md
   - name: GitHub repositories
     href: community/repositories.md
-  - name: Issues >>
+  - name: Issues ›
     href: https://aka.ms/spdev-issues
-  - name: Feature Requests >>
+  - name: Feature Requests ›
     href: http://aka.ms/spdev-uservoice
-  - name: SharePoint Dev at YouTube >>
+  - name: SharePoint Dev at YouTube ›
     href: http://aka.ms/spdev-videos
-  - name: OfficeDev Twitter >>
+  - name: OfficeDev Twitter ›
     href: https://twitter.com/officedev
-  - name: Deveveloper Forum >>
+  - name: Deveveloper Forum ›
     href: http://aka.ms/spdev-community