doc: proofread of the all reST sources (no content change)

Normalize reST sources with best practice and KISS in mind.

to name a few points:

- simplify reST tables
- make use of ``literal`` markup for monospace rendering
- fix code-blocks for better rendering in HTML
- normalize section header markup
- limit all lines to a maximum of 79 characters
- add option -H to the sudo command used in code blocks
- drop useless indentation of lists
- ...

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

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

docs/dev/contribution_guide.rst

@@ -1,66 +1,68 @@
+=================
 How to contribute
------------------
+=================
 
 Prime directives: Privacy, Hackability
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+======================================
 
-Searx has two prime directives, privacy-by-design and hackability. The
+Searx has two prime directives, **privacy-by-design and hackability** .  The
 hackability comes in three levels:
 
--  support of search engines
--  plugins to alter search behaviour
--  hacking searx itself
+- support of search engines
+- plugins to alter search behaviour
+- hacking searx itself
 
-Note the lack of "world domination" among the directives.
-Searx has no intention of wide mass-adoption, rounded
-corners, etc. The prime directive "privacy" deserves a separate
-chapter, as it's quite uncommon unfortunately.
+Note the lack of "world domination" among the directives.  Searx has no
+intention of wide mass-adoption, rounded corners, etc.  The prime directive
+"privacy" deserves a separate chapter, as it's quite uncommon unfortunately.
 
 Privacy-by-design
-^^^^^^^^^^^^^^^^^
+-----------------
 
-Searx was born out of the need for a privacy-respecting search tool
-which can be extended easily to maximize both its search and its
-privacy protecting capabilities.
+Searx was born out of the need for a **privacy-respecting** search tool which
+can be extended easily to maximize both, its search and its privacy protecting
+capabilities.
 
-A few widely used features work differently or turned off by default or not implemented
-at all as a consequence of privacy-by-design.
+A few widely used features work differently or turned off by default or not
+implemented at all **as a consequence of privacy-by-design**.
 
-If a feature reduces the privacy preserving aspects of searx, it
-should be switched off by default or should not implemented at all.
-There are plenty of search engines already providing such features.
-If a feature reduces the protection of searx, users must be
-informed about the effect of choosing to enable it. Features
-that protect privacy but differ from the expectations of the
-user should also be explained.
+If a feature reduces the privacy preserving aspects of searx, it should be
+switched off by default or should not implemented at all.  There are plenty of
+search engines already providing such features.  If a feature reduces the
+protection of searx, users must be informed about the effect of choosing to
+enable it.  Features that protect privacy but differ from the expectations of
+the user should also be explained.
 
-Also, if you think that something works weird with searx,
-it's might be because of the tool you use is designed in a way to interfere with
-the privacy respect. Submitting a bugreport to the vendor of the tool that
-misbehaves might be a good feedback to reconsider the disrespect to
-its customers (e.g. GET vs POST requests in various browsers).
+Also, if you think that something works weird with searx, it's might be because
+of the tool you use is designed in a way to interfere with the privacy respect.
+Submitting a bugreport to the vendor of the tool that misbehaves might be a good
+feedback to reconsider the disrespect to its customers (e.g. ``GET`` vs ``POST``
+requests in various browsers).
 
-Remember the other prime directive of searx is to be hackable, so if the
-above privacy concerns do not fancy you, simply fork it.
+Remember the other prime directive of searx is to be hackable, so if the above
+privacy concerns do not fancy you, simply fork it.
 
-Happy hacking.
+  *Happy hacking.*
 
 Code
-~~~~
+====
+
+.. _PEP8: https://www.python.org/dev/peps/pep-0008/
+
 
 In order to submit a patch, please follow the steps below:
 
 - Follow coding conventions.
 
-  - PEP8 standards apply, except the convention of line length
-
+  - PEP8_ standards apply, except the convention of line length
   - Maximum line length is 120 characters
 
-- Check if your code breaks existing tests. If so, update the tests or fix your code.
+- Check if your code breaks existing tests.  If so, update the tests or fix your
+  code.
 
 - If your code can be unit-tested, add unit tests.
 
-- Add yourself to the AUTHORS file.
+- Add yourself to the :origin:`AUTHORS.rst` file.
 
 - Create a pull request.
 
@@ -68,31 +70,20 @@ For more help on getting started with searx development, see :ref:`devquickstart
 
 
 Translation
-~~~~~~~~~~~
+===========
 
-Translation currently takes place on
-`transifex <https://transifex.com/projects/p/searx>`__.
+Translation currently takes place on :ref:`transifex <translation>`.
+
+.. caution::
+
+   Please, do not update translation files in the repo.
 
-**Please, do not update translation files in the repo.**
 
 Documentation
-~~~~~~~~~~~~~
+=============
 
-The documentation is built using Sphinx. So in order to be able to generate the required
-files, you have to install it on your system. (It can be installed easily using pip.)
+.. admonition::  ToDo
 
-1. Checkout the gh-pages branch.
+   docs are no longer in gh-branch
 
-2. Edit the rst file you wish to update. Or create a new rst file and place it under the appropriate folder.
-
-3. Build the documentation using Sphinx.
-
-4. Add the updated and created files of these extension:
-
-   - .rst
-
-   - .html
-
-   - .txt
-
-6. Create a pull request.
+   Update this chapter and document the /docs workflow!!