Add some SEO information to ease search

[Natim]

Improve Float to Int and Int to Float search engine results.

Refs elm/compiler#852

[process-bot]

Thanks for the pull request! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[process-bot]

Thanks for the pull request! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[evancz]

In the docs in development code I changed the header to Int to Float / Float to Int instead. I think it reads nicer. Thank you for the suggestion!

[evancz]

In the docs in development code I changed the header to Int to Float / Float to Int instead. I think it reads nicer. Thank you for the suggestion!