Fix #433: Add content and change the thumbnail image for the ratios concept card

[vinitamurthi]

Explanation

This PR changes the content of the ratios concept card and also adds a new thumbnail for it.
Thumbnail Image:

Concept card content:

Fixes #433

Checklist

• The PR title starts with "Fix #bugnum: ", followed by a short, clear summary of the changes. (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• The PR explanation includes the words "Fixes #bugnum: ..." (or "Fixes part of #bugnum" if the PR only partially fixes an issue).
• The PR follows the style guide.
• The PR does not contain any unnecessary auto-generated code from Android Studio.
• The PR is made from a branch that's not called "develop".
• The PR is made from a branch that is up-to-date with "develop".
• The PR's branch is based on "develop" and not on any other branch.
• The PR is assigned to an appropriate reviewer in both the Assignees and the Reviewers sections.

[rt4914]

LGTM.

[seanlip]

LGTM from my end (just with regards to the data added), thanks @vinitamurthi!

[BenHenning]

Thanks @vinitamurthi!