Blockly default branches on GitHub now called `main`

[Maribeth Moffatt]

Hello Block Builders,

You can stop reading here if you do not interact with Blockly via GitHub.

We've just renamed our default branches to `main` across all of our repositories. Standardizing the branch names should make it easier for new contributors to work on the project across multiple repositories.

Additionally, we will no longer be updating the `master` branch in blockly. It may be deleted in the future. The final commit to `master` has been tagged as `master-old` and this tag will remain. You can always get to the latest released version of Blockly from the npm or GitHub releases.

To recap:

• In blockly, `develop` has been renamed to `main` and the `master` branch will no longer be updated.
• In blockly-samples, `master` has been renamed to `main`.
• In blockly-keyboard-experimentation, there is no change as the default branch is already called `main`.

You can update your local references to these branches by following these instructions. Please post any questions in the forum.

Thanks,

Maribeth