Update readme

.prettierignore

@@ -1,3 +1,4 @@
 combined.json
 /misc
 *.json
+README.md

README.MD

@@ -1,29 +1,114 @@
 # Combine-json
 
-Combine-json is a CLI tool that combines all json files found in a directory into one big json file using streaming.
+Combine-json is a CLI tool that combines all json files found in a directory into one big json file using streaming to avoid out-of-memory.
 
-It takes as argument a directory in which to find the json files and a output file name in which the json files will combined.
-The json file will be created in the directory where the CLI is used.
+The output JSON file contains an array with all the inputed JSON files.
+So if your JSON file contained `{ "id": 1 }` it will be stored in the output file like this:
+
+Input files:
+
+file 1:
+```json
+{ "id": 1 }
+```
+
+file 2:
+```json
+{ "id": 2 }
+```
+
+Output file:
+```json
+[
+  { "id": 1 },
+  { "id": 2 }
+]
+```
+
+**Array exception**:
+There is one exception to this rule. If your JSON file contains an array, it will be deconstructed in the final file (_could become an option please make an issue if you'd like that_).
+
+Input files:
+
+```json
+[ 1, 2, 3 ]
+```
+
+```json
+{ "id": 1 }
+```
+
+Output file:
+
+```json
+[
+  1,
+  2,
+  3,
+  { "id": 1 }
+]
+```
 
-It accepts either json object files and json array files.
-It accepts relative path but also fully qualified paths.
 
 ## Installation
+
+CLI:
+
 ```bash
-npm i
-npm run link
+npx combine-json [options]
 ```
 
+Library:
+
+```bash
+# yarn
+yarn add combine-json
+
+# npm
+npm install combine-json
+```
+
+
 ## Usage
-`combine-json [inputDir] [outputFile(optionnal)]`
+
+Combine-json has two options:
+
+- Input dir: the path to the directory containing all the jsons.
+- Output file _optional_: path to the output file.
+
+It accepts relative path but also fully qualified paths.
+
+### CLI usage:
+
 ```bash
-combine-json directory
+combine-json --input-dir <dir-path> --output-file <file-path> (default: "combined.json")
 ```
-default output file is combined.json at the root of where you execute the cli.
+
+**Example**
+```bash
+combine-json /data combined_data.json
+```
+
+### Library usage
+
+```js
+const { combineJson } = require('./src');
+
+(async () => {
+  await combineJson({ inputDir: 'misc', outputFile: 'combined_data.json' });
+})();
+```
+
+### Example
+
+Using the JSON files present in `misc`, you can observe the outputed file [misc_output.json](./misc_output.json)
 
 ## Try it out
-Go at the root of the CLI
+
+At the root of the repository use the following:
+
 ```bash
-combine-json misc
+npx combine-json misc
 ```
-it will generate a combined.json file with all the json object found in misc.
+
+it will generate a combined.json file with all the JSON objects found in misc.