added docs for vmui in victorialogs (#4494)

docs/VictoriaLogs/QuickStart.md

@@ -96,4 +96,11 @@ as demo for running fluentbit in kubernetes with VictoriaLogs:
 
 ## How to query logs in VictoriaLogs
 
-See details in [these docs](https://docs.victoriametrics.com/VictoriaLogs/querying).
+You can query logs with [LogsQL](https://docs.victoriametrics.com/VictoriaLogs/LogsQL.html) using the following options:
+
+- [VMUI](https://docs.victoriametrics.com/VictoriaLogs/querying/#vmui) - a web-based UI for querying logs.
+- [Command-line interface](https://docs.victoriametrics.com/VictoriaLogs/querying/#command-line-interface).
+
+<img src="querying/vmui.png" width="800" />
+
+See more details in [these docs](https://docs.victoriametrics.com/VictoriaLogs/querying).

docs/VictoriaLogs/README.md

@@ -17,6 +17,7 @@ It provides the following key features:
 - VictoriaLogs can handle much bigger data volumes than ElasticSearch and Grafana Loki when running on comparable hardware.
 - VictoriaLogs supports multitenancy - see [these docs](#multitenancy).
 - VictoriaLogs supports out of order logs' ingestion aka backfilling.
+- VictoriaLogs provides simple web UI for querying logs - see [these docs](https://docs.victoriametrics.com/VictoriaLogs/querying/#web-ui).
 
 VictoriaLogs is at Preview stage now. It is ready for evaluation in production and verifying claims given above.
 It isn't recommended migrating from existing logging solutions to VictoriaLogs Preview in general case yet.

docs/VictoriaLogs/querying/README.md

@@ -48,6 +48,28 @@ curl http://localhost:9428/select/logsql/query -H 'AccountID: 12' -H 'ProjectID:
 The number of requests to `/select/logsql/query` can be [monitored](https://docs.victoriametrics.com/VictoriaLogs/#monitoring)
 with `vl_http_requests_total{path="/select/logsql/query"}` metric.
 
+## VMUI
+
+VictoriaLogs provides a simple UI for logs query and exploration. The UI is available at `http://victorialogs:9428/vmui`.
+The UI allows exploring query results via tables or JSON-result:
+
+<img src="vmui.png" width="800" />
+
+There are three modes of displaying query results:
+
+- `Group` - results are displayed as a table with rows grouped by stream and fields for filtering.
+- `Table` - displays query results as a table.
+- `JSON` - displays raw JSON response from `/select/logsql/query` endpoint.
+
+This is the first version that has minimal functionality. It comes with the following limitations:
+
+- The number of query results is always limited to 1000 lines.
+- A tenant 0 is always used in queries.
+
+These limitations will be removed in future versions.
+
+To get around the current limitations, you can use an alternative - the [command line interface](#command-line).
+
 ## Command-line
 
 VictoriaLogs integrates well with `curl` and other command-line tools during querying because of the following features: