Add better support for enum values, with Xcode tags.

Xcode tag syntax means that you can now click on the link in the docs, and it will take you straight to the enum. This should make it a little bit easier for clients to see what options are available.

Author: Sherlouk

Scripts/semantic-convention/templates/SemanticAttributes.swift.j2

@@ -28,6 +28,7 @@ import Foundation
 public enum {{enum}}: String {
 
     {%- for attribute in attributes | unique(attribute="fqn") %}
+    {%- set class_name = attribute.fqn | to_camelcase(True) ~ "Values" %}
     /**
     {{attribute.brief | to_doc_brief}}.
     {%- if attribute.examples %}
@@ -52,7 +53,11 @@ public enum {{enum}}: String {
     - Warning: Deprecated • {{attribute.deprecated | to_doc_brief}}.
     {%- endif %}
 
+    {%- if attribute.is_enum %}
+    - Requires: Value should be one of [`{{enum}}.{{class_name}}`](x-source-tag://otel{{class_name}}) (of type `{{to_swift_return_type(attribute.attr_type|lower)}}`)
+    {% else %}
     - Requires: Value type should be `{{to_swift_return_type(attribute.attr_type|lower)}}`
+    {% endif -%}
     */
     {%- if attribute.deprecated %}
     @available(*, deprecated)
@@ -78,6 +83,7 @@ public enum {{enum}}: String {
     /**
     {{attribute.brief | to_doc_brief}}.
     */
+    /// - Tag: otel{{class_name}}
     {%- if attribute.attr_type.custom_values %}
     public struct {{class_name}}: CustomStringConvertible {
         {%- for member in attribute.attr_type.members %}
@@ -90,7 +96,8 @@ public enum {{enum}}: String {
         /**
         swift.
         */
-        public static let swift = TelemetrySdkLanguageValues("swift"){% endif %}
+        public static let swift = TelemetrySdkLanguageValues("swift")
+        {%- endif %}
 
         internal let value: String