Add detailed alt text to decision tree images

[acrall]

There are two detailed diagrams on the home page of the planning kit. currently, the alt text provided for the images is not very descriptive so would not provide the details required to understand the diagram. Needs updating

[elletjies]

#21

[acrall]

Tagging @brynnelliott

[elletjies]

@OscarSiba is there another way we can present this info to make it more legible?

[OscarSiba]

@OscarSiba is there another way we can present this info to make it more legible?

Do we by any chance know where the original graphic is @elletjies?

[elletjies]

@OscarSiba you can find it here: https://github.com/CarpentryConnect/carpentryconnect.org/tree/master/img

[elletjies]

Closing this since the alt text was added