Initial documentation for regulator config files

Added documentation for the phosphor-regulators config file.  The
phosphor-regulators application configures and monitors voltage
regulators.

This commit contains the README, an example config file, and
documentation for the root object within the config file.  Subsequent
commits will add documentation for the other JSON objects in the config
file.

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: Ia5cea4bb5a4d4053c1537ce385fcd3c903423e56
diff --git a/phosphor-regulators/examples/config_file.json b/phosphor-regulators/examples/config_file.json
new file mode 100644
index 0000000..701322d
--- /dev/null
+++ b/phosphor-regulators/examples/config_file.json
@@ -0,0 +1,106 @@
+{
+  "comments": [ "Config file for a FooBar one-chassis system" ],
+
+  "rules": [
+    {
+      "comments": [ "Sets output voltage for a PMBus regulator rail" ],
+      "id": "set_voltage_rule",
+      "actions": [
+        {
+          "pmbus_write_vout_command": {
+            "format": "linear"
+          }
+        }
+      ]
+    },
+
+    {
+      "comments": [ "Reads sensors from a PMBus regulator rail" ],
+      "id": "read_sensors_rule",
+      "actions": [
+        {
+          "comments": [ "Read output voltage from READ_VOUT." ],
+          "pmbus_read_sensor": {
+            "type": "vout",
+            "command": "0x8B",
+            "format": "linear_16"
+          }
+        },
+
+        {
+          "comments": [ "Read output current from READ_IOUT." ],
+          "pmbus_read_sensor": {
+            "type": "iout",
+            "command": "0x8C",
+            "format": "linear_11"
+          }
+        },
+
+        {
+          "comments": [ "Read temperature from READ_TEMPERATURE_1." ],
+          "pmbus_read_sensor": {
+            "type": "temperature",
+            "command": "0x8D",
+            "format": "linear_11"
+          }
+        }
+      ]
+    }
+  ],
+
+  "chassis": [
+    {
+      "comments": [ "Chassis number 1 containing CPUs and memory" ],
+      "number": 1,
+      "devices": [
+        {
+          "comments": [ "IR35221 regulator producing the Vdd rail" ],
+          "id": "vdd_regulator",
+          "is_regulator": true,
+          "fru": "/system/chassis/motherboard/regulator1",
+          "i2c_interface": {
+            "bus": 1,
+            "address": "0x70"
+          },
+          "rails": [
+            {
+              "comments": [ "Vdd rail" ],
+              "id": "vdd",
+              "configuration": {
+                "volts": 1.03,
+                "rule_id": "set_voltage_rule"
+              },
+              "sensor_monitoring": {
+                "rule_id": "read_sensors_rule"
+              }
+            }
+          ]
+        },
+
+        {
+          "comments": [ "IR35221 regulator producing the Vio rail" ],
+          "id": "vio_regulator",
+          "is_regulator": true,
+          "fru": "/system/chassis/motherboard/regulator2",
+          "i2c_interface": {
+            "bus": 1,
+            "address": "0x71"
+          },
+          "rails": [
+            {
+              "comments": [ "Vio rail" ],
+              "id": "vio",
+              "configuration": {
+                "volts": 1.1,
+                "rule_id": "set_voltage_rule"
+              },
+              "sensor_monitoring": {
+                "rule_id": "read_sensors_rule"
+              }
+            }
+          ]
+        }
+      ]
+    }
+  ]
+}