Add a README

README.md

+wp-mat
+===
+
+Wordpress plugin that automatically filters all uploaded files through
+[MAT2](https://0xacab.org/jvoisin/mat2) in order to remove potentially
+identifying metadata.
+
+Meant to be used in combination with
+[wp-mat-server](https://git.autistici.org/noblogs/wp-mat-server), a
+simple API wrapper for mat2.