Improve issue template and README

[tsalo]

Changes proposed:

• Add link to project proposal issue creation.
• Be more explicit about where to write contents in issue template.

[richford]

LGTM :rocket:

[dmoracze]

Thought:

<!-- Add the basic research question(s) your project will attempt to answer below this line -->

Means that we'll likely have this line included in the issue. You could say something like

<!-- Replace this line with the basic research question(s) your project will attempt to answer -->

[tsalo]

@dmoracze the lines are comments, though, so they won't appear in the rendered issue. I worry that saying "replace" might lead folks to place their information between the comment strings (i.e., <!-- and -->).

[dmoracze]

Ah ok, I think it's good then.