[enh] engines: add about variable

move meta information from comment to the about variable
so the preferences, the documentation can show these information

searx/engines/gigablast.py

@@ -1,14 +1,6 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 """
  Gigablast (Web)
-
- @website     https://gigablast.com
- @provide-api yes (https://gigablast.com/api.html)
-
- @using-api   yes
- @results     XML
- @stable      yes
- @parse       url, title, content
 """
 # pylint: disable=missing-function-docstring, invalid-name
 
@@ -18,6 +10,16 @@ from urllib.parse import urlencode
 # from searx import logger
 from searx.poolrequests import get
 
+# about
+about = {
+    "website": 'https://www.gigablast.com',
+    "wikidata_id": 'Q3105449',
+    "official_api_documentation": 'https://gigablast.com/api.html',
+    "use_official_api": True,
+    "require_api_key": False,
+    "results": 'JSON',
+}
+
 # engine dependent config
 categories = ['general']
 # gigablast's pagination is totally damaged, don't use it