Move develop into master

[becky-gilbert]

This moves the latest bits of work on develop into the master branch:

• Adds the new consent template for Project GARDEN (see https://github.com/lookit/lookit-api/issues/1266, https://github.com/lookit/ember-lookit-frameplayer/pull/333)
• Fixes a typo in the documentation (https://github.com/lookit/ember-lookit-frameplayer/commit/51c9e97957228f7de00d2fe7e9cc3082ffb1dcf9)
• Fixes a link in the README (https://github.com/lookit/ember-lookit-frameplayer/commit/cef88879d7df16cd565a64fc159ab176556a8e9d)

Moving these changes onto master means that these updates become part of the 'default' experiment runner version (for new experiment builds), and will show up as the latest version when researchers click the 'Check for updates' button.