Remove guidelines index page.

The mainly lists the pages found under `guidelines/`, as the hugo site
now automatically lists these. The rest of the information on this page
is also either broadly out of date or of negligable value. Remove the
index completely as we will be removing the guidelines section anyway.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

content/_index.md

@@ -70,7 +70,7 @@ Apertis provides a number of pre-built images for Intel (64-bit) and ARM (32-bit
 * [Mailing lists](https://lists.apertis.org/)
 * [Architectural documentation]( {{< ref "/architecture" >}}) 
 * [Development guides]( {{< ref "/guides" >}} )
-* [Development guidelines]( {{< ref "/guidelines/_index.md" >}} )
+* [Development guidelines]( {{< ref "guidelines" >}} )
 * [Concept designs]( {{< ref "concepts" >}} )
 * [Supported APIs](https://developer.apertis.org/latest/apis.html)
 * [App developer portal](https://developer.apertis.org)

content/guidelines/_index.md

-+++
-date = "2019-11-26"
-weight = 100
-
-title = "Guidelines"
-
-aliases = [
-    "/old-wiki/Guidelines"
-]
-+++
-
-# Guidelines
-
-SDK guidelines for application developers, focusing on security. These
-are a series of guidelines and examples for various aspects of
-developing on and in the Apertis libraries and applications. They assume
-a good level of competence with programming in C, and familiarity with
-the underlying libraries Apertis uses, such as
-[GLib](https://developer.gnome.org/glib/stable/). A good set of
-introductory guidelines for using GLib and related libraries are the
-[GNOME Programming
-Guidelines](https://developer.gnome.org/programming-guidelines/unstable/).
-
-To get started, skim each of the [General
-guidelines](#general-guidelines) pages, each of which has a
-summary at the top. Specific topics are covered in the [Specific
-how-tos](#specific-how-tos) section, which can be used more
-like a reference manual.
-
-The [external links](#external-links) point to further
-resources, which can be quite comprehensive and are worth reading.
-
-## General guidelines
-
-  - [How to submit a patch in Apertis
-    project](https://designs.apertis.org/latest/contribution-process.html)
-  - [Packaging release
-    workflow]( {{< ref "/guidelines/howtoreleasepackages.md" >}} )
-  - [Module setup]( {{< ref "/guidelines/module_setup.md" >}} )
-  - [Licensing](https://designs.apertis.org/latest/license-applying.html)
-  - [Coding
-    conventions](https://designs.apertis.org/latest/coding_conventions.html)
-  - [Upstream
-    first](https://designs.apertis.org/latest/contribution-process.html#upstream-first-policy)
-  - [Version control]( {{< ref "/guidelines/version_control.md" >}} )
-  - [API design]( {{< ref "/guidelines/api_design.md" >}} )
-  - [API stability]( {{< ref "/guidelines/api_stability.md" >}} )
-  - [Memory management]( {{< ref "/guidelines/memory_management.md" >}} )
-  - [Tooling]( {{< ref "/guidelines/tooling.md" >}} )
-  - [Unit testing]( {{< ref "/guidelines/unit_testing.md" >}} )
-  - [API documentation]( {{< ref "/guidelines/api_documentation.md" >}} )
-  - [Code submission
-    checklist](https://designs.apertis.org/latest/contribution-checklist.html)
-
-## Specific how-tos
-
-  - [How to develop on
-    devices]( {{< ref "/guidelines/howtodevelopondevices.md" >}} )
-  - [Enabling new hardware]( {{< ref "/enabling_new_hardware.md" >}} )
-  - [Package maintenance]( {{< ref "/package_maintenance.md" >}} )
-  - [JSON parsing]( {{< ref "/guidelines/json_parsing.md" >}} )
-  - [XML parsing]( {{< ref "/guidelines/xml_parsing.md" >}} )
-  - [GSettings]( {{< ref "/guidelines/gsettings.md" >}} )
-  - [D-Bus services]( {{< ref "/guidelines/d-bus_services.md" >}} )
-  - [Introspection]( {{< ref "/guidelines/introspection.md" >}} )
-  - [SQLite]( {{< ref "/guidelines/sqlite.md" >}} )
-  - [Tracker]( {{< ref "/guidelines/tracker.md" >}} )
-  - [AppArmor]( {{< ref "/guidelines/apparmor.md" >}} )
-  - [Threading]( {{< ref "/guidelines/threading.md" >}} )
-  - [Filesystem access]( {{< ref "/guidelines/filesystem_access.md" >}} )
-  - [Logging]( {{< ref "/guidelines/logging.md" >}} )
-  - [Internationalization]( {{< ref "/guidelines/internationalization.md" >}} )
-  - [Processes]( {{< ref "/guidelines/processes.md" >}} )
-  - [Writing test cases]( {{< ref "/qa/test_cases_guidelines.md" >}} )
-  - [Add linters to a project]( {{< ref "/guidelines/add_linters_to_a_project.md" >}} )
-  - [Building, Patching And Maintaining The Apertis
-    Kernel]( {{< ref "/guidelines/buildingpatchingandmaintainingtheapertiskernel.md" >}} )
-
-## External links
-
-  - [CERT secure C coding guidelines](https://www.securecoding.cert.org/confluence/display/seccode/CERT+C+Coding+Standard)
-  - [MISRA C coding guidelines overview](http://en.wikipedia.org/wiki/MISRA_C) (guidelines themselves are non-free)
-  - [GNOME Programming Guidelines](https://developer.gnome.org/programming-guidelines/unstable/)
-  - [Google C++ guidelines](https://google.github.io/styleguide/cppguide.html#General_Naming_Rules)
-    — useful general advice, but often not specific to GLib-style C, and
-    sometimes contradictory to the GNOME Programming Guidelines, which
-    are preferred