Add the 'get involved' blurb automatically to blog posts

[JoblersTune]

Every blog post needs to end with a standard paragraph

As we are open source, you can easily check our work on GitHub. If the work mentioned here inspired you, we welcome your contributions. You can join our community slack or participate in the next community call, which takes place each second Wednesday of the month.

If you want to stay updated with all open opportunities and news from the Interledger Foundation, you can subscribe to our newsletter.

Instead of relying on everyone remembering individually, this should be automated, or embedded directly, or at very least part of the blog template Google Doc.

[huijing]

Resolved by #105