[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/pubmed.py

@@ -1,14 +1,6 @@
-#!/usr/bin/env python
-
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
  PubMed (Scholar publications)
- @website     https://www.ncbi.nlm.nih.gov/pubmed/
- @provide-api yes (https://www.ncbi.nlm.nih.gov/home/develop/api/)
- @using-api   yes
- @results     XML
- @stable      yes
- @parse       url, title, publishedDate, content
- More info on api: https://www.ncbi.nlm.nih.gov/books/NBK25501/
 """
 
 from flask_babel import gettext
@@ -17,6 +9,18 @@ from datetime import datetime
 from urllib.parse import urlencode
 from searx.poolrequests import get
 
+# about
+about = {
+    "website": 'https://www.ncbi.nlm.nih.gov/pubmed/',
+    "wikidata_id": 'Q1540899',
+    "official_api_documentation": {
+        'url': 'https://www.ncbi.nlm.nih.gov/home/develop/api/',
+        'comment': 'More info on api: https://www.ncbi.nlm.nih.gov/books/NBK25501/'
+    },
+    "use_official_api": True,
+    "require_api_key": False,
+    "results": 'XML',
+}
 
 categories = ['science']