Add extracted tools: CitrineOS, OpenOCPP, ShapeShifter

- CitrineOS core extracted (CSMS OCPP 2.0.1)
- OpenOCPP extracted (firmware OCPP 1.6J/2.0.1)
- ShapeShifter library installed (pip install -e)
- ShapeShifter specification extracted
- EVerest extracted

TODO updated with progress

tools/EVerest-main/docs/source/explanation/linux-yocto/index.rst

@@ -0,0 +1,19 @@
+.. _exp_linux_yocto:
+
+#########################
+Linux / Yocto
+#########################
+
+You will find different explanations about using EVerest with
+Linux and Yocto in the following sections:
+
+.. toctree::
+    :maxdepth: 1
+
+    setting-up-linux-os
+    building-yocto
+    ota-updates
+    partitioning-schemes-for-rauc-ota
+
+Make sure to check out the :doc:`How-to-guide on cross-compilation </how-to-guides/yocto-cross-compilation>`
+for a step-by-step guide on how to cross-compile EVerest for a Yocto-based Linux system.