foundation board: address needs of different user types (#1203)

This proposal was prompted by @MMesch, who brought it up at the [NixCon
governance
workshop](https://discourse.nixos.org/t/nixcon-governance-workshop/32705/6#line-between-community-and-companies-2)
and also gave [a talk on the subject at the 23.11 ZHF
workshop](https://discourse.nixos.org/t/zurich-23-11-zhf-hackathon-and-ux-workshop-report/37848#lightning-talks-3),
and I agree this should be made explicit.

community/teams/foundation-board.tt

@@ -38,6 +38,12 @@
     <li>
       Handle sponsoring and donations
     </li>
+    <li>
+      Encourage contributions by individuals and organisations alike
+    </li>
+    <li>
+      Balance the interests of volunteers, commercial actors, and public institutions
+    </li>
     <li>
       Build and maintain beneficial and collaborative relationships
     </li>