Adding DD_DOGSTATSD_TAG_CARDINALITY capability

[anthony-pastor]

To add this missing field: #21

[vboulineau]

Hey @anthony-pastor,

Thanks for your contribution.
To validate your PR, please:

• Document the new parameter in README.md
• Bump Chart version
• Use a more descriptive commit message (that can be used as a changelog)

[anthony-pastor]

Hey @anthony-pastor,

Thanks for your contribution.
To validate your PR, please:

* Document the new parameter in `README.md`

* Bump Chart version

* Use a more descriptive commit message (that can be used as a changelog)

I've added a commit to address your comments.