Add pinecone demo container image

[networkException]

This pull request adds the configuration and CI steps to build and publish a container wrapping the dendrite-demo-pinecone command as well as fixes a sentence structure issue in the pull request template.

As this does not touch any go source code no tests have been added

Pull Request Checklist

• [x] I have added tests for PR or I have justified why this PR doesn't need tests.
• [x] Pull request includes a sign off

Signed-off-by: networkException <[email protected]>

[neilalexander]

LGTM, but unfortunately we can't accept a sign-off statement from a pseudonym. Please either update your sign-off line in the PR or email us a private sign-off to [email protected] with a link to this PR.

[networkException]

I sent a private sign-off to the email