Maintain the folder structure in 'content'

[saurabhdaware]

Is your feature request related to a problem? Please describe.
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Current abell can only understand content/ that has following structure

content/
  -> my-cool-blog
    -> index.md

Describe the solution you'd like
A clear and concise description of what you want to happen.
It should also support

content/
  -> my-section
    -> my-cool-blog
      -> index.md

So in the output also we'll get the same path.

Additional context
Add any other context or screenshots about the feature request here.
This will need major refactoring of the whole abell.

[saurabhdaware]

Working on this! (feat-keep-dir-structure)