Documentation issues

[chiraganand]

• README.md is missing IBM.csv. It should be done using https://github.com/JuliaPackaging/ArtifactUtils.jl
• Finance demo has some import and other errors.
• getindex() methods are not getting documented at all, they are missing from the published API documentation.

[SusanXKDR]

@san-ath , please update this with what has been done already. It will be good to also include what is yet to be done, so that we can tackle it in the next update of TSFrames.

Once this is done, please close out the issue and Chirag can take steps to release the package with changes to the documentation.

[san-ath]

A pull request has been submitted to fix README.md, demo_finance.md, and some other package dependencies for the documentation. The API documentation issues are yet to be fixed.