docs: Add appendix showing date filter changes

[claremacrae]

Description

Add a detailed appendix in filters.md showing the changes in date filter search results since the previous release.

The table was populated by using text from the DueDateField.test.due_date approval tests.approved.md approval test file, so guaranteed to be correct.

/CC @ilandikov

Motivation and Context

I want to be clear to users what the changes in behaviour are in the upcoming release.

How has this been tested?

Viewing docs locally.

Screenshots (if appropriate)

Additions to the table of contents in filters.md

---

New red warning 1:

---

New red warning 2:

---

Start of appendix:

---

Example with real differences:

---

Types of changes

Changes visible to users:

• Documentation (prefix: docs - improvements to any documentation content for users)

Checklist

• My code follows the code style of this project and passes yarn run lint.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• My change has adequate Unit Test coverage.

Terms

• My contribution follow this project's contributing guide
• I agree to follow this project's Code of Conduct