Add issue template and other fixes

Author: mosuem

.github/ISSUE_TEMPLATE/yaml_edit.md

@@ -0,0 +1,5 @@
+---
+name: "package:yaml_edit"
+about: "Create a bug or file a feature request against package:yaml_edit."
+labels: "package:yaml_edit"
+---

pkgs/yaml_edit/pubspec.yaml

@@ -2,7 +2,7 @@ name: yaml_edit
 version: 2.2.2-wip
 description: >-
   A library for YAML manipulation with comment and whitespace preservation.
-repository: https://github.com/dart-lang/yaml_edit
+repository: https://github.com/dart-lang/tools/tree/main/pkgs/yaml_edit
 
 issue_tracker: https://github.com/dart-lang/yaml_edit/issues