Added "Optional Features" section in Firmware config

[DerFuchs]

To account for latest Klipper version.

Build will fail otherwise when too many options have been selected. (Saying there's no memory left)

[yebo29]

Addresses #231

[thijstriemstra]

Addresses #231

+1

[thijstriemstra]

After upgrading to klipper 0.13.x the settings page changed again. I used the following for klipper expander:

[timmit99]

After upgrading to klipper 0.13.x the settings page changed again. I used the following for klipper expander:

Any chance you can grab a cleaner image with the title bar that we can add into the instructions to replace this one?

May need @DerFuchs to upload that photo to their branch to add to this PR, but doing that and editing the text instructions to match and i can merge the changes!

[Walmtech]

Just found this when updating is this what you need?

[timmit99]

Just found this when updating is this what you need?

Not really, If i am to merge this change request, I need the author (@DerFuchs) to add that image into their branch so it merges into the mainline repository. =)

[thijstriemstra]

Not really, If i am to merge this change request, I need the author (@DerFuchs) to add that image into their branch so it merges into the mainline repository. =)

unless someone makes a new pull request, with the same image you've just been give permission to use. just using it would be beneficial to the community.

[DerFuchs]

Thank you for pointing out :)
I Updated the readme file accordingly.

[thijstriemstra]

this should be good to go @timmit99