[Docs] Smallish overhaul of the docs (#5281)

* Fix up Common functions doc

* Add to extra commands to flashing doc

* Rearrange and touch up Macros

* Expand Newbs Flashing guide

* Update process_record documentation

* Add git to best practices name in sidebar

* Expand FAQ for build/flashing

* Add deprecated info to functions

* Update docs/feature_macros.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/feature_macros.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/flashing.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/flashing.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/keymap.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/newbs_flashing.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/newbs_flashing.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/custom_quantum_functions.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/faq_build.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/feature_macros.md

Co-Authored-By: drashna <drashna@live.com>

* Update docs/keymap.md

Co-Authored-By: drashna <drashna@live.com>

* Fix up Common functions doc

* Make pre-init example accurate

* Update docs/custom_quantum_functions.md

Co-Authored-By: drashna <drashna@live.com>

* Zadig Driver catchall

* Spelling Depriciated

* Completely remove fn_actions section

docs/_summary.md

@@ -3,7 +3,7 @@
   * [Building Your First Firmware](newbs_building_firmware.md)
   * [Flashing Firmware](newbs_flashing.md)
   * [Testing and Debugging](newbs_testing_debugging.md)
-  * [Best Practices](newbs_best_practices.md)
+  * [Git Best Practices](newbs_best_practices.md)
   * [Learning Resources](newbs_learn_more_resources.md)
 
 * [QMK Basics](README.md)