[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>

2 files changed, 110 insertions, 0 deletions

diff --git a/searx/info/en/about.md b/searx/info/en/about.md
new file mode 100644
index 000000000..9f323870e
--- /dev/null
+++ b/searx/info/en/about.md
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+# About SearXNG
+
+SearXNG is a fork from the well-known [searx] [metasearch engine], aggregating
+the results of other {{link('search engines', 'preferences')}} while not
+storing information about its users.
+
+More about SearXNG ...
+
+* [SearXNG sources]({{GIT_URL}})
+* [weblate]
+
+
+## Why use it?
+
+* SearXNG may not offer you as personalised results as Google, but it doesn't
+  generate a profile about you.
+
+* SearXNG doesn't care about what you search for, never shares anything with a
+  third party, and it can't be used to compromise you.
+
+* SearXNG is free software, the code is 100% open and you can help to make it
+  better.  See more on [SearXNG sources]({{GIT_URL}}).
+
+If you do care about privacy, want to be a conscious user, or otherwise believe
+in digital freedom, make SearXNG your default search engine or run it on your
+own server
+
+## Technical details - How does it work?
+
+SearXNG is a [metasearch engine], inspired by the [seeks project].  It provides
+basic privacy by mixing your queries with searches on other platforms without
+storing search data. Queries are made using a POST request on every browser
+(except Chromium-based browsers*).  Therefore they show up in neither our logs,
+nor your url history. In the case of Chromium-based browser users there is an
+exception: searx uses the search bar to perform GET requests.  SearXNG can be
+added to your browser's search bar; moreover, it can be set as the default
+search engine.
+
+## How to set as the default search engine?
+
+SearXNG supports [OpenSearch].  For more information on changing your default
+search engine, see your browser's documentation:
+
+* [Firefox]
+* [Microsoft Edge]
+* Chromium-based browsers [only add websites that the user navigates to without
+  a path.](https://www.chromium.org/tab-to-search)
+
+## Where to find anonymous usage statistics of this instance ?
+
+{{link('Stats page', 'stats')}} contains some useful data about the engines
+used.
+
+## How can I make it my own?
+
+SearXNG appreciates your concern regarding logs, so take the code from the
+[SearXNG project]({{GIT_URL}}) and run it yourself!
+
+Add your instance to this [list of public
+instances]({{get_setting('brand.public_instances')}}) to help other people
+reclaim their privacy and make the Internet freer!  The more decentralized the
+Internet is, the more freedom we have!
+
+## Where are the docs & code of this instance?
+
+See the [SearXNG docs]({{get_setting('brand.docs_url')}}) and [SearXNG
+sources]({{GIT_URL}})
+
+[searx]: https://github.com/searx/searx
+[metasearch engine]: https://en.wikipedia.org/wiki/Metasearch_engine
+[weblate]: https://weblate.bubu1.eu/projects/searxng/
+[seeks project]: https://beniz.github.io/seeks/
+[OpenSearch]: https://github.com/dewitt/opensearch/blob/master/opensearch-1-1-draft-6.md
+[Firefox]: https://support.mozilla.org/en-US/kb/add-or-remove-search-engine-firefox
+[Microsoft Edge]: https://support.microsoft.com/en-us/help/4028574/microsoft-edge-change-the-default-search-engine
diff --git a/searx/info/en/search-syntax.md b/searx/info/en/search-syntax.md
new file mode 100644
index 000000000..ae820dfbc
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+++ b/searx/info/en/search-syntax.md
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+# Search syntax
+
+SearXNG allows you to modify the default categories, engines and search language
+via the search query.
+
+Prefix `!` to set category and engine names.
+
+Prefix: `:` to set the language.
+
+Abbrevations of the engines and languages are also accepted.  Engine/category
+modifiers are chainable and inclusive.  E.g. with {{search('!map !ddg !wp paris')}}
+search in map category **and** duckduckgo **and** wikipedia for
+`paris`.
+
+See the {{link('preferences', 'preferences')}} for the list of engines,
+categories and languages.
+
+## Examples
+
+Search in wikipedia for `paris`:
+
+* {{search('!wp paris')}}
+* {{search('!wikipedia paris')}}
+
+Search in category `map` for `paris`:
+
+* {{search('!map paris')}}
+
+Image search:
+
+* {{search('!images Wau Holland')}}
+
+Custom language in wikipedia:
+
+* {{search(':fr !wp Wau Holland')}}