Added links to logos suitable for Discourse

README.md

@@ -60,6 +60,8 @@ Initial settings used for `community.coops.tech` when it was created:
 * contact url: https://www.coops.tech/
 * notification email: discourse@community.coops.tech
 * site contact username: system
+* logo url: https://wiki.coops.tech/wiki/File:Cotech-blue.png
+* logo small url: https://wiki.coops.tech/wiki/File:Cotech-blue-text.png
 * company short name: CoTech
 * company full name: Cooperative Technologists
 * company domain: coops.tech