fix links

external/contribute/vscode/vscode.md

 ---
 layout: page
-permalink: /external/contribute/vscode
+permalink: /external/contribute/vscode/
 shortcut: contribute:vscode
 redirect_from:
   - /cards/contribute:vscode
   - /external/cards/contribute:vscode
 ---
+
 # Contribute using Visual Studio Code
 
 This shows how to use Visual Studio Code to write a howto-card:

external/contribute/web-ide/web-ide.md

 ---
 layout: page
-permalink: /external/contribute/web-ide
+permalink: /external/contribute/web-ide/
 shortcut: contribute:web-ide
 redirect_from:
   - /cards/contribute:web-ide
   - /external/cards/contribute:web-ide
 ---
+
 # Contribute using Gitlab Web IDE
 
 This shows how to use Gitlab Web IDE to add or edit a howto-card: