Linkify references and add papers in readme

[LSYS]

Some of the Lexical diversity/lexical richness studies have been cited in the Readme.

However, the readme.rst does not include links to these articles. Nor does the repo include those articles (pdf).

For example, McCarthy and Jarvis 2007 is not linkified in the readme. It is also not included in the repo as a pdf (preferably in the docs/literature folder). Would be nice to linkify the references and add the papers to the repo.

What's actionable: For each missing reference (e.g., McCarthy and Jarvis 2007, Šišková 2012, etc.):

• Replace study X in the readme.rst as a hyperlink (DOIs preferred). For example, replace study X with study X <link to study>_ (see this for a guide on adding links to external web pages in .rst)
• Add the pdf article (if freely available) to docs/literature folder (e.g. as studyX.pdf)

[rutvikk05]

Hello, I would like to work on this issue. Could you please assign it to me?

[Sreetama2001]

@LSYS I am working on this issue, Could you assign me this?

[Sreetama2001]

What's actionable: For each missing reference (e.g., McCarthy and Jarvis 2007, Šišková 2012, etc.):

• Replace study X in the readme.rst as a hyperlink (DOIs preferred). For example, replace study X with study X <link to study>_ (see this for a guide on adding links to external web pages in .rst)
• Add the pdf article (if freely available) to docs/literature folder (e.g. as studyX.pdf)

Should I link the documents to the external page(containing the pdf ) or to the pdf directing inside the folder it is stored for e.g. docs/literature? @LSYS

[Sreetama2001]

@LSYS I guess it is better if we add detailed citations and follow-up papers of the same in another readme.rst

[Sreetama2001]

@LSYS can you please check the PR and add suggestions or accept it !!