Add Missing Introductory Information for POUR Mapping Table

REFERENCE: Annex B, Table B.2

The current Table B.2 maps EN 301 549 clauses to the WCAG POUR principles. However, unlike the previously included Functional Performance Statement (FPS) mapping table, this POUR table lacks accompanying introductory information.

PROPOSED CHANGE

Depending on whether this was intentional or not to get rid of the mapping to the Functional Performance Statements.

• If removing the FPS mapping was intentional: remove the description before and examples after the new table they inserted - mapping to WCAG POUR.
• If not intentional: add back in the FPS mapping and move the WCAG POUR table either to another annex or move it after the example tables (which were examples for the FPS mapping table).
• If needed, add introductory information and examples about the POUR mapping table.

Related to issue #559 (closed)