Updated README.md to clarify access to editor through index.html

[IgorWilbert]

Fixes #240

Make sure these boxes are checked before your pull request (PR) is ready to be reviewed and merged. Thanks!

• tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR -- or run tests locally with grunt jasmine
• code is in uniquely-named feature branch and has no merge conflicts
• PR is descriptively titled
• PR body includes fixes #0000-style reference to original issue #
• ask @publiclab/reviewers for help, in a comment below

We're happy to help you get this ready -- don't be afraid to ask for help, and don't be discouraged if your tests fail at first!

If tests do fail, click on the red X to learn why by reading the logs.

Please be sure you've reviewed our contribution guidelines at https://publiclab.org/contributing-to-public-lab-software

We have a loose schedule of reviewing and pulling in changes every Tuesday and Friday, and publishing changes on Fridays.

Thanks!

[rexagod]

Hey! Could we explicitly mention something like CORS offline issue and provide a link to this the referenced issue as a solution in the Readme? What do you think?

[IgorWilbert]

@rexagod sounds like a good idea, thank you! I updated README.md accordingly.

[VladimirMikulic]

@IgorWilbert 👍

[jywarren]

Very nice, thank you!!