Update documentation, start with blog section

[stmh]

Please review the changes I made to the documentation. I moved stuff around to make it more clear where to find what and also tried to harmonize the used terminology.

I started also with 2 blog postings;

• one about the overall architecture of phabalicious
• one showing how to work with secrets (reusing the small talk I gave in the backend working group)

I'd like to extend the blog-section in the future, describing smaller pieces of functionality and cross-post them to the factorial blog. The next post will be one on how to create a drupal site from scratch and add a minimal fabfile for that.

The diffs are hard to read, I recommend to check out the branch and run

yarn install
yarn docs:dev

and review the generated documentation at https://localhost:8080

[nataliaalves03]

I loved the blog posts, it's very useful to understand phab with a different narrative than using the documentation :) I follow shibin' suggestions, I found the same small typing fixes.

[stmh]

thanks everyone, highly appreciate!