update contributing links

- Handlebars 2.0 with canary builds
- Use the correct canary build URL
Merge pull request #2441 from sly7-7/update-contributing-links

Update contributing links. Closes #2440
Removing outdated example from DS.Store documentation. #2442
Merge pull request #2444 from cohitre/storeDocumentation

Removing outdated example from DS.Store documentation. #2442