Unless you're going to reference your blog-posts in the documentation and you're willing to keep such documentation updated, I'd strongly recommend you to focus on improving the documentation instead of writing long walls of text on the internals.

If I imagine myself using your framework, well, I would be very angry at you if I had to stop writing code, leave my editor and go read your shilly-shally.

I would focus on:

1) Topics like "Application structure", "Application Deployment", "Application command-line interface" (which at the moment of writing are all just a "TODO").

2) Sample code. A 30 lines example is worth a thousand word blog post

3) More sample code. Ideally, one for every crucial part (cookies? session? middlewares?)

By the way: I see there are some examples, great! But add some more comments to your examples.

4) Blog post on internals.

I'd delay the blog post upon internals because I guess that since you'll be receiving a lot of feedback you might want to change things in the internals thus "invalidating" your blog posts.

P.s: congratulations on using doxygen so well! I wish more project had such a well done documentation!

p.p.s: I hope you won't find my comment rude or anything, I actually like this project.