Docker.md in pghero-1.5.3

- old
+ new
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 # PgHero for Docker
 
-:fire: [Get it](https://github.com/bmorton/pghero_solo)
+PgHero is available as a [Docker image](https://hub.docker.com/r/ankane/pghero/).
 
-More instructions coming soon
+```sh
+docker run -ti -e DATABASE_URL=postgres://user:password@hostname:5432/dbname -p 8080:8080 ankane/pghero
+```
+
+And visit [http://localhost:8080](http://localhost:8080).
+
+## Query Stats
+
+Query stats can be enabled from the dashboard. If you run into issues, [view the guide](Query-Stats.md).
+
+## Historical Query Stats
+
+To track query stats over time, create a table to store them.
+
+```sql
+CREATE TABLE "pghero_query_stats" (
+  "id" serial primary key,
+  "database" text,
+  "user" text,
+  "query" text,
+  "query_hash" bigint,
+  "total_time" float,
+  "calls" bigint,
+  "captured_at" timestamp
+)
+CREATE INDEX ON "pghero_query_stats" ("database", "captured_at")
+```
+
+Schedule the task below to run every 5 minutes.
+
+```sh
+docker run -ti -e DATABASE_URL=... ankane/pghero bin/rake pghero:capture_query_stats
+```
+
+After this, a time range slider will appear on the Queries tab.
+
+## Credits
+
+Thanks to [Brian Morton](https://github.com/bmorton) for the [original Docker image](https://github.com/bmorton/pghero_solo).