Added SiteText field to all elements

In my head, each field should have a single text field that will be the bulk of the text content for the final webpage. This field should be required in the database so that there is content for a page. I have updated a version of the schema that fulfills this requirement. All major fields have 1 (and exactly 1) SiteText field which is just string/text. This information is the data general data that each team will collect. Feel free to modify this/let me know if I am diverging from what y'all think is best.