Update documents for CLA

[Sen-real]

Objective

Update documents due to recent changes about CLA.

Abstractions

• Update CONTRIBUTING.md due to changes about CLA.
• Update CLA config file to provide our email address to contributors who choose to send us signed CLA files.
• Remove CLA section from DevReadme.md because we have a separate CONTRIBUTING.md.
• Remove CLA files from this repo, as we now have CLA bot to provide links to common CLA documents as a comment in the PR of each new comer.

Currently the CLA documents that the CLA bot asks contributors to sign are here:

• https://github.com/Autodesk/autodesk.github.io/releases/download/1.0/ADSK.Form.Corp.Contrib.Agmt.for.Open.Source.docx
• https://github.com/Autodesk/autodesk.github.io/releases/download/1.0/ADSK.Form.Ind.Contrib.Agmt.for.Open.Source.docx

Tests performed

Have read the changes in preview mode.

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