Create SECURITY.md

[pedrocruzio]

[what-the-diff[bot]]

• The file SECURITY.md was added to the .github directory
• This is a security policy for tea, which includes information on how to report vulnerabilities and what versions are supported by this program
• It also lists exclusions of things that do not constitute as security vulnerabilities in tea (e.g., clickjacking)

[jonchang]

I suggest putting the files in this repository instead: https://github.com/teaxyz/.github

This means that the relevant sections will automatically appear in all repositories in the teaxyz organization, rather than on a repository-by-repositoy basis.

[jonchang]

Looks like this pull request is against the wrong repository? Should be this one: https://github.com/teaxyz/.github

[mxcl]

@pedrocruzio pls re-open in the correct place