[docs][Tutorial] Using Multiple Themes Together.

Summary

When new Gatsby users come across the concept of themes they become excited about the possibilities it offers. Even more when they see the added advantage of using themes over starters, with more emphasis on using “Multiple themes” on one site.

The concept is explained in this part of the theme doc. However, the docs could benefit from a tutorial on how to use multiple themes at once.

Some recommended topics to cover:

• Using multiple themes in gatsby-config
• Component shadowing This list is more extensive, but further research is necessary

Motivation

To provide Gatsby users with a detailed tutorial, on understanding how multiple themes can work together in Gatsby. Practical examples are always helpful.

Location in Doc

https://www.gatsbyjs.org/tutorial/using-multiple-themes-together

[ehowey]

If you look now there is some progress in that PR. There is about 75% of a first draft in there. Hopefully I will finish a first draft in the next few days.

[Ekwuno]

Yes! That sounds great. Thank you 💜