Added documentation to README.md

Author: mdb-gtenrreiro

README.md

@@ -1 +1,118 @@
 # datagen
+
+Datagen is a CLI utility to generate JSON data using fake values.
+It generates data to a file, or to Kafka. 
+
+## Usage
+
+### Examples
+**Generate data to a file**
+```
+./datagen create --filesystem --from ./templates/myTemplate.json
+```
+
+It generates data using `myTemplate.json` to a file in `./data/data.txt`. 
+
+**Generate data to Kafka**
+```
+./datagen create --kafka --topic myTopic --from ./templates/myTemplate.json
+```
+
+It generates data using `myTemplate.json` to a kafka topic named `myTopic`. The data will continue to be generated until datagen is stopped. 
+
+## Templates
+Datagen relies on valid JSON template documents to generate the data. The templates allow for the creation of fake data. Fake data can be specified using the syntax `fake:{<fake specifier>}` where `<fake specifier>` must be replaced with one of:
+
+**Numbers**
+```
+number:<min>,<max>
+int8
+int16
+int32
+int64
+uint8
+uint16
+uint32
+uint64
+float32
+float32range:<min>,<max>
+float64
+float64range:<min>,<max>
+```
+**Strings**
+```
+digit
+letter
+lexify:<string>
+numerify:<string>
+```
+**Person**
+```
+person
+name
+nameprefix
+namesuffix
+firstname
+lastname
+gender
+ssn
+contact
+email
+phone
+phoneformatted
+```
+
+...TODO Add more here
+
+### Template Example
+
+```
+{
+    "id": "fake:{number:1,11}",
+    "name": "fake:{uint64}",
+    "department": "IT",
+    "designation": "Product Manager",
+    "username": "fake:{username}",
+    "password": "fake:{password}",
+    "address1": "fake:{address}",
+    "latitude": "fake:{latitude}",
+    "longitude": "fake:{longitude}",
+    "latitudeInRange": "fake:{latituderange:23.1,56.7}",
+    "address": {
+        "city": "Mumbai",
+        "state": "Maharashtra",
+        "country": "India"
+    }
+}
+```
+
+The above template would produce JSON documents like the following:
+
+```
+{
+    "address": {
+        "city": "Mumbai",
+        "country": "India",
+        "state": "Maharashtra"
+    },
+    "address1": {
+        "address": "New Mexico Stehrtown Valleyschester743号 ",
+        "street": "Valleyschester743号",
+        "city": "Stehrtown",
+        "state": "New Mexico",
+        "zip": "36339",
+        "country": "New Caledonia",
+        "latitude": -49.659845,
+        "longitude": 18.110164
+    },
+    "department": "IT",
+    "designation": "Product Manager",
+    "id": 5,
+    "latitude": -1.947745,
+    "latitudeInRange": 29.420478,
+    "longitude": -27.482948,
+    "name": 5427729115751982900,
+    "password": "vGdku\u0026$ZGi8#",
+    "username": "Kiehn4009"
+}
+```