docs: add comments for the url_host_type enum

Author: anonrig

include/ada/url_base.h

@@ -17,8 +17,18 @@ namespace ada {
  * Type of URL host as an enum.
  */
 enum url_host_type : uint8_t {
+  /**
+   * Represents common URLs such as "https://www.google.com"
+   */
   DEFAULT = 0,
+  /**
+   * Represents ipv4 addresses such as "http://127.0.0.1"
+   */
   IPV4 = 1,
+  /**
+   * Represents ipv6 addresses such as
+   * "http://[2001:db8:3333:4444:5555:6666:7777:8888]"
+   */
   IPV6 = 2,
 };