Bump issue notebook month

.vscode/notebooks/verification.github-issues

@@ -14,7 +14,7 @@
   {
     "kind": 2,
     "language": "github-issues",
-    "value": "$repos=repo:microsoft/vscode repo:microsoft/vscode-internalbacklog repo:microsoft/vscode-remote-release repo:microsoft/vscode-js-debug repo:microsoft/vscode-pull-request-github repo:microsoft/vscode-github-issue-notebooks \n$milestone=milestone:\"June 2020\"",
+    "value": "$repos=repo:microsoft/vscode repo:microsoft/vscode-internalbacklog repo:microsoft/vscode-remote-release repo:microsoft/vscode-js-debug repo:microsoft/vscode-pull-request-github repo:microsoft/vscode-github-issue-notebooks \n$milestone=milestone:\"July 2020\"",
     "editable": true
   },
   {
@@ -44,7 +44,8 @@
   {
     "kind": 1,
     "language": "markdown",
-    "value": "### All"
+    "value": "### All",
+    "editable": true
   },
   {
     "kind": 2,