add an issue template for applying for joining security membership.

[LiZhenCheng9527]

What would you like to be added:
An issue template for Company or organisation applying to join private distributors list.
Why is this needed:
If a company or organisation uses Kurator. we should give them a way to join the private distribution list for security vulnerabilities. Avoid losses due to Kurator vulnerabilities.

[LiZhenCheng9527]

/assign @LiZhenCheng9527

[Xieql]

how about "Add an issue template to apply for joining the security membership."