[mod] replace /help by /info pages and include pages in project docs

This patch implements a bolierplate to share content from info-pages of the
SearXNG instance (URL /info) with the project documentation (path /docs/user).

The info pages are using Markdown (CommonMark), to include them in the project
documentation (reST) the myst-parser [1] is used in the Sphinx-doc build chain.

If base_url is known (defined in settings.yml) links to the instance are also
inserted into the project documentation::

    searxng_extra/docs_prebuild

[1] https://www.sphinx-doc.org/en/master/usage/markdown.html

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/webapp.py

@@ -56,8 +56,9 @@ from searx import (
     get_setting,
     settings,
     searx_debug,
-    user_help,
 )
+
+from searx import infopage
 from searx.data import ENGINE_DESCRIPTIONS
 from searx.results import Timing, UnresponsiveEngine
 from searx.settings_defaults import OUTPUT_FORMATS
@@ -660,6 +661,7 @@ def index():
         # fmt: off
         'index.html',
         selected_categories=get_selected_categories(request.preferences, request.form),
+        current_locale = request.preferences.get_value("locale"),
         # fmt: on
     )
 
@@ -864,6 +866,7 @@ def search():
         unresponsive_engines = __get_translated_errors(
             result_container.unresponsive_engines
         ),
+        current_locale = request.preferences.get_value("locale"),
         current_language = match_language(
             search_query.lang,
             settings['search']['languages'],
@@ -898,19 +901,29 @@ def __get_translated_errors(unresponsive_engines: Iterable[UnresponsiveEngine]):
 @app.route('/about', methods=['GET'])
 def about():
     """Redirect to about page"""
-    return redirect(url_for('help_page', pagename='about'))
+    locale = request.preferences.get_value('locale')
+    return redirect(url_for('info', pagename='about', locale=locale))
 
 
-@app.route('/help/en/<pagename>', methods=['GET'])
-def help_page(pagename):
-    """Render help page"""
-    page = user_help.PAGES.get(pagename)
+_INFO_PAGES = infopage.InfoPageSet(infopage.MistletoePage)
 
+
+@app.route('/info/<locale>/<pagename>', methods=['GET'])
+def info(pagename, locale):
+    """Render page of online user documentation"""
+
+    locale = locale or request.preferences.get_value('locale')
+    page = _INFO_PAGES.get_page(pagename, locale)
+    if page is None:
+        page = _INFO_PAGES.get_page(pagename)
     if page is None:
         flask.abort(404)
 
     return render(
-        'help.html', page=user_help.PAGES[pagename], all_pages=user_help.PAGES.items(), page_filename=pagename
+        'info.html',
+        all_pages=_INFO_PAGES.all_pages,
+        active_page=page,
+        active_pagename=pagename,
     )
 
 
@@ -1411,7 +1424,6 @@ werkzeug_reloader = flask_run_development or (searx_debug and __name__ == "__mai
 if not werkzeug_reloader or (werkzeug_reloader and os.environ.get("WERKZEUG_RUN_MAIN") == "true"):
     plugin_initialize(app)
     search_initialize(enable_checker=True, check_network=True, enable_metrics=settings['general']['enable_metrics'])
-    user_help.render(app)
 
 
 def run():