Create a Pull Request Template with Unresolved Checkboxes

[mmaclay]

Every Pull Request will have a list of checkboxes that need to be closed in order to merge.
some example ideas (to be refined):

• Did you update the index.rst to show your page in the table of contents?
• Did you remove any internal LASP resources, links, keys, or information?
• Did you ensure your contribution is general enough and not LASP, user, or case-specific?

[mmaclay]

Created this issue in order to test slack integrations.