Add README

See bisq-network/github#19
See bisq-network/roles#40

README.adoc

@@ -0,0 +1,9 @@
+= Bisq network "numbers"
+
+This repository is for tracking key "numbers" related to the Bisq network, for example, https://docs.google.com/spreadsheets/d/1M8y2cIlHv5Hx5UAt4WZ961Ac8xaNSLiiavjxabNf0qc/edit#gid=966637110[Global Trading Volume in USD] (Google Sheet).
+
+If you have questions or comments, come chat with us in the `#numbers` channel of the https://bisq.network/slack-invite[Bisq Slack workspace].
+
+If you have a specific request or issue related to these numbers or spreadsheets, please open a GitHub issue in this repository.
+
+See also the https://github.com/bisq-network/roles/issues/40[number cruncher] role.