feat(chart): Adding maintainer url

Each maintainer can have an optional URL. There are seceral use
cases for providing a URL instead of an email address:
- The case where a maintainer wants to hide their email address
  behind a webform for personal security
- When the maintainer is an organization and feedback should
  go to an issue queue

This change:
- Adds the proto field for url
- Updates the generated files for the chart proto
- Includes linting for the url
- Updates the docs to include the url

Closes #3056

_proto/hapi/chart/metadata.proto

@@ -25,6 +25,9 @@ message Maintainer {
 
 	// Email is an optional email address to contact the named maintainer
 	string email = 2;
+
+	// Url is an optional URL to an address for the named maintainer
+	string url = 3;
 }
 
 //	Metadata for a Chart file. This models the structure of a Chart.yaml file.

docs/charts.md

@@ -52,6 +52,7 @@ sources:
 maintainers: # (optional)
   - name: The maintainer's name (required for each maintainer)
     email: The maintainer's email (optional for each maintainer)
+    url: A URL for the maintainer (optional for each maintainer)
 engine: gotpl # The name of the template engine (optional, defaults to gotpl)
 icon: A URL to an SVG or PNG image to be used as an icon (optional).
 appVersion: The version of the app that this contains (optional). This needn't be SemVer.

pkg/lint/rules/chartfile.go

@@ -141,6 +141,8 @@ func validateChartMaintainer(cf *chart.Metadata) error {
 			return errors.New("each maintainer requires a name")
 		} else if maintainer.Email != "" && !govalidator.IsEmail(maintainer.Email) {
 			return fmt.Errorf("invalid email '%s' for maintainer '%s'", maintainer.Email, maintainer.Name)
+		} else if maintainer.Url != "" && !govalidator.IsURL(maintainer.Url) {
+			return fmt.Errorf("invalid url '%s' for maintainer '%s'", maintainer.Url, maintainer.Name)
 		}
 	}
 	return nil