Blog configuration should be fixed

[adpaco-aws]

The publication of the first blog post forced us to make some quick changes to the configuration (see #6 and #7). But this configuration is not the right one, since links to other posts and images still need to be pasted "as is" (when we could be using the more elegant syntax to include references). This also means that testing is not 100% reliable, and deployments can fail when the tested version was working.

[celinval]

From the little research I've done, this is a github pages issue. Links generated using absolute syntax do not include the name of the repository, so it's incorrectly generated.

Let's say we have:

![My image](/assets/my_image.png)

When we build the page, the link will actually map to:

http://[user|org].github.io/assets/my_image.png

instead of

http://[user|org].github.io/[repo]/assets/my_image.png

So there's two options that would be testable in a PR level (but that requires the fork to have the same repository name -- i.e.: kani-verifier-blog):

1. Use absolute path but include the name of the repository:

![My image](/kani-verifier-blog/assets/my_image.png)

2. Use the embedded HTML version with a reference to the baseurl:

<img src="/{{site.baseurl}}/assets/my_image.png" alt="My image" />

[celinval]

Note that both solutions will not render in the markdown github preview.