ICM: Readme subsection extracted.

Author: dmitry-ivanov

README.md

@@ -19,6 +19,7 @@ Prevents overlapping for Laravel console commands.
 - [Usage](#usage)
 - [Strategies](#strategies)
 - [Advanced](#advanced)
+  - [Common mutex for several commands](#common-mutex-for-several-commands)
 - [Troubleshooting](#troubleshooting)
   - [Trait included, but nothing happens?](#trait-included-but-nothing-happens)
   - [Several traits conflict?](#several-traits-conflict)
@@ -98,6 +99,8 @@ class MyProtectedCommand extends Command
 
 ## Advanced
 
+### Common mutex for several commands
+
 Sometimes it is useful to set common mutex for a several commands. You can easily achieve this by setting them the same mutex name.
 By default, mutex name is generated based on a command's name and arguments. To change this, just override `getMutexName` method in your command: