Add doc for activity_dashboard dashboard (#4)

Author: misraved

dashboards/activity_dashboard.pp

@@ -1,5 +1,7 @@
 dashboard "activity_dashboard" {
-  title = "Audit Log Activity Dashboard"
+
+  title         = "Audit Log Activity Dashboard"
+  documentation = file("./dashboards/docs/activity_dashboard.md")
 
   tags = {
     type    = "Dashboard"

dashboards/docs/activity_dashboard.md

@@ -0,0 +1,10 @@
+This dashboard answers the following questions:
+
+- How many GCP Audit Logs are recorded?
+- How many logs are generated per project?
+- How many logs are generated per log type?
+- Who are the top actors initiating activities?
+- What are the top source IPs (excluding GCP internal sources)?
+- What are the top GCP services generating logs?
+- What are the top events recorded in the audit logs?
+