Add documentation

[preeti98]

This is a documentation generated using doxygen and a pull request in response to issue #97 .
Please do let me know for further improvements.

[vinay0410]

Hi @preeti98 ,
I am not able to generate documentation on my local machine since you've hard coded project's in the Doxyfile, which is specific to your machine only.
Please change that, so anyone can generate Documentation on their machine.
Also, try to submit only 1 commit for a single issue. If you accidentally make multiple commits, then please merge them into one in future.

[preeti98]

@vinay0410 Sir, I will make sure to merge multiple commits from next time.
Could you please review my later commit?

[vinay0410]

There are some things I forgot to mention:

1. You aren't supposed to push Documentation generated by doxygen in your pull request. I wasn't aware of that since I haven't used doxygen.
2. Second as convention suggests rename Documentation to docs.
3. By changing paths, I meant use of relative paths, so that we can use Travis CI's virtual container.
   Create an empty folder called docs, put the Doxyfile in the root of the project i.e in dl-DetectionSuite directory.
4. Change Input to .
5. And Change Output to ./docs/
6. You may open a different pull request.

Finally, what we want is that travis ci after Compilation automatically generates documentation and updates the docs directory which can be published to Github Pages.

Please accomplish the first 6 tasks to proceed.

[vinay0410]

Closing this as #104 will fulfil the requirements.