Add missing example ts_schemas and fix web_gui link

scripts/plugins/example/ts_schemas/min.lua

@@ -0,0 +1,32 @@
+--
+-- (C) 2020 - ntop.org
+--
+
+-- This file contains timeseries defintions which have minute granularity
+
+local ts_utils = require "ts_utils_core"
+local schema
+
+-- Define a schema "example:active_hosts" as a gauge (suitable for
+-- instant values).
+schema = ts_utils.newSchema("example:active_hosts", {
+  step = 60,
+  metrics_type = ts_utils.metrics.gauge,
+})
+
+schema:addTag("ifid")
+schema:addMetric("num_hosts")
+
+-- ##############################################
+
+-- Define a schema "example:num_requests" as counter (suitable for
+-- cumulative values)
+schema = ts_utils.newSchema("example:num_requests", {
+  step = 60,
+  metrics_type = ts_utils.metrics.counter,
+})
+
+schema:addTag("ifid")
+schema:addTag("endpoint")
+schema:addMetric("as_client")
+schema:addMetric("as_server")