Update broken link to google dp library in introduction.rst

[patsab]

Description

The link was wrong. It pointed to the IBM DP Library instead of the Google one. I changed the link in the file introduction.rst

Affected Dependencies

None

How has this been tested?

Checked if the link works in my fork.

Checklist

• [X] I have followed the Contribution Guidelines and Code of Conduct
• [X] I have commented my code following the OpenMined Styleguide
• [] I have labeled this PR with the relevant Type labels
• [X] My changes are covered by tests

[patsab]

It seems that I don't have the rights to add a label to the Pull Request

[jeamick]

LGTM

[chinmayshah99]

Thank you @patsab! Good catch :)