Fix Planck and Preonic builds (#5658)

Fix Planck and Preonic builds (#5658)

* Planck: Copy contents of Planck rules.mk to each revision

* Planck: Delete Planck rules.mk

* Planck: Concatenate duplicate rules

Concatenate rules that are set and then overridden into one setting.

* Preonic: Copy contents of Preonic rules.mk to each revision

* Preonic: Delete Preonic rules.mk

* Preonic: Concatenate duplicate rules

Concatenate rules that are set and then overridden into one setting.

* Planck: Delete non-specific Bootloader settings from revs. 1 and 2

Deleted BOOTLOADER setting code block, as the checks were only valid for revs. 3-5 and the Planck Light.

Neither Planck rev1 or rev2 set the bootloader via rules.mk, so there's no setting of BOOTLOADER in their rules.mk files.

* Preonic: Fix BOOTLOADER settings code blocks

* Preonic: delete extra blank lines from rules.mk files

* Preonic: delete AVR-type hardware config blocks from rev3

* Update Planck and Preonic readme files

- update Hardware Supported
- update/add Install Examples
- update Docs paragraph

* Enable Bootmagic Lite where it is disabled

Enabled Bootmagic Lite for:

- Planck Light
- Planck revs. 1-5
- Preonic revs. 1 and 2

* Remove `planck_grid` from LAYOUTS rule for all Planck revisions

Community has landed on `ortho_4x12`, which is already set; `planck_grid` is redundant.