modify README.md

Author: ExpCoderWeb

README.md

@@ -3,7 +3,71 @@
 
 [![Maintainability](https://api.codeclimate.com/v1/badges/0ecdf71fcddffc9d9b3e/maintainability)](https://codeclimate.com/github/ExpCoderWeb/fullstack-javascript-project-46/maintainability) [![Test Coverage](https://api.codeclimate.com/v1/badges/0ecdf71fcddffc9d9b3e/test_coverage)](https://codeclimate.com/github/ExpCoderWeb/fullstack-javascript-project-46/test_coverage)
 
+### Overview
+
+**"Difference Finder"** is a program that determines the difference between two data structures. It displays how the second file has changed compared to the first one. This is a common task for which there are numerous online services, for example, http://www.jsondiff.com/. This mechanism is used when outputting tests or tracking changes in configuration files.
+
+**Utility features**:
+
+- Support for different input formats: JSON, YAML
+- Output in stylish (by default), plain text, and JSON format
+
+### Minimal system requirements:
+- Unix terminal
+- Node.js: version from 18.x
+
+### Utility setup
+1. Clone the repo with the following command:
+```bash
+git clone git@github.com:ExpCoderWeb/fullstack-javascript-project-46.git
+```
+2. Enter the root directory of the package with the command:
+```bash
+cd fullstack-javascript-project-46
+```
+3. Install the necessary dependencies with the command:
+```bash
+npm ci
+```
+4. Create a symbolic link to the package in order to make the utility to run from any directory of the system using the command: 
+```bash
+npm link
+```
+
+### Usage
+```bash
+Usage: gendiff [options] <filepath1> <filepath2>
+
+Compares two configuration files and shows a difference.
+
+Options:
+  -V, --version        output the version number
+  -f, --format [type]  output format (default: "stylish")
+  -h, --help           output usage information
+```
+Program can handle both absolute and relative filepaths. Compared files can be in different formats. Example:
+```bash
+gendiff /home/user/__fixtures__/file1.json __fixtures__/file2.yml
+```
+
+This library can be installed as a dependency in any other NPM package as well. An example of how other packages could use genDiff:
+```bash
+import genDiff from '@hexlet/code';
+
+const diff = genDiff(filepath1, filepath2, formatName);
+console.log(diff);
+```
+
 ### Demonstration
 
-#### 1. Comparison of flat files (JSON):
-[![asciicast](https://asciinema.org/a/P902Vkx6vLx3oAVjEOB3W8oor.svg)](https://asciinema.org/a/P902Vkx6vLx3oAVjEOB3W8oor)
+#### 1. Comparison of flat files:
+[![asciicast](https://asciinema.org/a/Tc8nH134MBp8TLBOkwke4eK1Y.svg)](https://asciinema.org/a/Tc8nH134MBp8TLBOkwke4eK1Y)
+
+#### 2. Comparison of nested files (format 'stylish'):
+[![asciicast](https://asciinema.org/a/R2vd2AmfaKWZAhdZq5yholDQN.svg)](https://asciinema.org/a/R2vd2AmfaKWZAhdZq5yholDQN)
+
+#### 3. Comparison of nested files (format 'plain'):
+[![asciicast](https://asciinema.org/a/xreCxFS8BDQ7EHDaMP9c7WK0S.svg)](https://asciinema.org/a/xreCxFS8BDQ7EHDaMP9c7WK0S)
+
+#### 4. Comparison of nested files (format 'json'):
+[![asciicast](https://asciinema.org/a/GAoKHeauTxNIpUXpUUFXb2izu.svg)](https://asciinema.org/a/GAoKHeauTxNIpUXpUUFXb2izu)