Added Email button to working groups page

[sanjayy-gowdaa]

Resolves #2774
Added Email button to he working groups page (matrix.org/templates/governing-board/working_groups.html), appearing after the Matrix button.
License: Apache License 2.0

[HarHarLinks]

Hi, thanks for working on this. The screenshot looks great, the code looks reasonable.

• Please provide the source of the email icon. Usually, media assets do not use code licenses.
• I have edited your description to follow this syntax so we make sure the issue gets closed: https://docs.github.com/en/issues/tracking-your-work-with-issues/using-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword
• Please ensure your editor follows the repo's .editorconfig, in this case following the linux convention of newlines at the end of files.

[sanjayy-gowdaa]

Thank you for your feedback and the helpful suggestions!

• The email icon is sourced from Material Icons at Google Fonts.
• Thanks for updating the description with the correct resolves tag. From next time, I’ll make sure to use the correct GitHub resolves tag myself.
• I will double-check my editor to ensure it respects the repo's .editorconfig and the Linux newline convention.

[HarHarLinks]

Thank you.

For reference, here is a link confirming that material icons are indeed licensed Apache 2.0: https://developers.google.com/fonts/docs/material_symbols#licensing

We need to find a way to include the original copyright notice along with the file to respect the license.

[HarHarLinks]

I can't find a copyright notice. Also not on https://github.com/google/material-design-icons. It seems Google does not understand how to open source.

@thibaultamartin how do you think should we proceed?