Add usage instructions.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

README.md

@@ -5,3 +5,69 @@
 Logish is a horizontally-scalable, highly-available, multi-tenant, log aggregation
 system inspired by Prometheus.  It is design to be very cost effective, as it does
 not index the contents of the logs, but rather a set of labels for each log steam.
+
+## Usage Instructions
+
+Logish is running in the ops-tools1 cluster.  You can query logs from that cluster
+using the following commands:
+
+```
+$ go get github.com/grafana/logish/cmd/logcli
+$ . $GOPATH/src/github.com/grafana/logish/env # env vars inc. URL, username etc
+$ logcli labels job
+https://logs-dev-ops-tools1.grafana.net/api/prom/label/job/values
+cortex-ops/consul
+cortex-ops/cortex-gw
+...
+$ logcli query '{job="cortex-ops/consul"}'
+https://logs-dev-ops-tools1.grafana.net/api/prom/query?query=%7Bjob%3D%22cortex-ops%2Fconsul%22%7D&limit=30&start=1529928228&end=1529931828&direction=backward&regexp=
+Common labels: {job="cortex-ops/consul", namespace="cortex-ops"}
+2018-06-25T12:52:09Z {instance="consul-8576459955-pl75w"} 2018/06/25 12:52:09 [INFO] raft: Snapshot to 475409 complete
+2018-06-25T12:52:09Z {instance="consul-8576459955-pl75w"} 2018/06/25 12:52:09 [INFO] raft: Compacting logs from 456973 to 465169
+```
+
+The `logcli` command is temporary until we have Grafana integration. The URLs of
+the requests are printed to help with integration work.
+
+```
+$ logcli help
+usage: logcpi [<flags>] <command> [<args> ...]
+
+A command-line for logish.
+
+Flags:
+  --help         Show context-sensitive help (also try --help-long and --help-man).
+  --addr="https://log-us.grafana.net"
+                 Server address.
+  --username=""  Username for HTTP basic auth.
+  --password=""  Password for HTTP basic auth.
+
+Commands:
+  help [<command>...]
+    Show help.
+
+  query [<flags>] <query> [<regex>]
+    Run a LogQL query.
+
+  labels <label>
+    Find values for a given label.
+
+$ logcli help query
+usage: logcpi query [<flags>] <query> [<regex>]
+
+Run a LogQL query.
+
+Flags:
+  --help         Show context-sensitive help (also try --help-long and --help-man).
+  --addr="https://log-us.grafana.net"
+                 Server address.
+  --username=""  Username for HTTP basic auth.
+  --password=""  Password for HTTP basic auth.
+  --limit=30     Limit on number of entries to print.
+  --since=1h     Lookback window.
+  --forward      Scan forwards through logs.
+
+Args:
+  <query>    eg '{foo="bar",baz="blip"}'
+  [<regex>]
+```

env

+export GRAFANA_ADDR=https://logs-dev-ops-tools1.grafana.net
+export GRAFANA_USERNAME=29
+export GRAFANA_PASSWORD=eyJrIjoiMzJmNDRjYjI1NGI1MGUxODc3NmIzNjhlZjRkM2QzMWE5OWU4ZjllZSIsIm4iOiJ0b20tcHJvbS10ZXN0IiwiaWQiOjUwMDB9