feat(copier.yaml): add author and email fields with validation

copier.yaml

@@ -49,6 +49,14 @@ project_license:
     - GPLv3
     - None
 
+author:
+  type: str
+  help: What is your name?
+  validator: >-
+    {% if not (author | regex_search('^[a-zA-Z][a-zA-Z ]+$')) %}
+    author must start with a letter, followed one or more letters or spaces
+    {% endif %}
+
 github_username:
   type: str
   help: What is your GitHub username?
@@ -57,6 +65,15 @@ github_username:
     github_username must start with a letter or digit, followed one or more letters, digits or dashes in lowercase only
     {% endif %}
 
+email:
+  default: "{{ github_username }}@"
+  type: str
+  help: What is your email?
+  validator: >-
+    {% if not (email | regex_search('^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$')) %}
+    email must be a valid email address
+    {% endif %}
+
 github_repo_name:
   default: "{{ project_name }}"
   type: str