Fix the choco push errors

[whihathac]

• Reduce the description to <4000 chars (Chocolatey gave an error when I tried to publish it)
• Updated version number to have additional suffix number to accommodate the need to re-publish packages in case of any publish errors
• Updated instructions in Readme.md on how to publish to Chocolatey
• Added .gitignore to skip uploading nupkg files in repo here.

[DavidAnson]

Looks good. This is currently in draft form - are you waiting to add anything?

[whihathac]

Yeah I wanted to wait for the Chocolatey package approval just in case anything new pops up!

[whihathac]

Btw here's the upload - https://chocolatey.org/packages/textanalysistoolnet.portable/2018.11.20.0 -> it's pending some approval.

[whihathac]

Weird. It's still stuck in pending approval.

[whihathac]

@DavidAnson - Package is approved! Here's the choco page: https://chocolatey.org/packages/textanalysistoolnet.portable

[DavidAnson]

Awesome, thank you! Should I merge this PR now?

[whihathac]

Yeah! Thanks David!