Linux.md in pghero-1.1.1

- old
+ new

@@ -3,11 +3,13 @@
 Packaged for:
 
 - Ubuntu 14.04 (Trusty)
 - Ubuntu 12.04 (Precise)
 - Debian 7 (Wheezy)
-- CentOS and RHEL 6
+- Debian 8 (Jesse)
+- CentOS / RHEL 6
+- CentOS / RHEL 7
 - Fedora 20
 - SUSE Linux Enterprise Server
 
 64-bit only
 
@@ -38,21 +40,41 @@
 echo "deb https://deb.packager.io/gh/pghero/pghero wheezy master" | sudo tee /etc/apt/sources.list.d/pghero.list
 sudo apt-get update
 sudo apt-get install pghero
 ```
 
-CentOS and RHEL 6
+Debian 8 (Jesse)
 
 ```sh
+wget -qO - https://deb.packager.io/key | sudo apt-key add -
+echo "deb https://deb.packager.io/gh/pghero/pghero jessie master" | sudo tee /etc/apt/sources.list.d/pghero.list
+sudo apt-get update
+sudo apt-get install pghero
+```
+
+CentOS / RHEL 6
+
+```sh
 sudo rpm --import https://rpm.packager.io/key
 echo "[pghero]
 name=Repository for pghero/pghero application.
 baseurl=https://rpm.packager.io/gh/pghero/pghero/centos6/master
 enabled=1" | sudo tee /etc/yum.repos.d/pghero.repo
 sudo yum install pghero
 ```
 
+CentOS / RHEL 7
+
+```sh
+sudo rpm --import https://rpm.packager.io/key
+echo "[pghero]
+name=Repository for pghero/pghero application.
+baseurl=https://rpm.packager.io/gh/pghero/pghero/centos7/master
+enabled=1" | sudo tee /etc/yum.repos.d/pghero.repo
+sudo yum install pghero
+```
+
 Fedora 20
 
 ```sh
 sudo rpm --import https://rpm.packager.io/key
 echo "[pghero]
@@ -123,9 +145,32 @@
 ```
 
 ## 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, "query" text, "total_time" float, "calls" bigint, "captured_at" timestamp)
+CREATE INDEX "index_pghero_query_stats_on_database_and_captured_at" ON "pghero_query_stats" ("database", "captured_at")
+```
+
+This table can be in the current database or another database. If another database, run:
+
+```sh
+sudo pghero config:set PGHERO_STATS_DATABASE_URL=...
+```
+
+Schedule the task below to run every 5 minutes.
+
+```sh
+sudo pghero run rake pghero:capture_query_stats
+```
+
+After this, a time range slider will appear on the Queries tab.
 
 ## System Stats
 
 CPU usage is available for Amazon RDS.  Add these variables to your environment:
 