MultiplayerSample Project README_LINUX.md provides incomplete commands to register Editor, Gems and Project

[LB-MichalRodzos]

Describe the bug
In section "Step 2. Register the engine, the project, and the Gems" of the MultiplayerSample Project README_LINUX.md the following commands are provided:

$HOME/o3de/scripts/o3de register --this-engine
$HOME/o3de/scripts/o3de register --all-gems-path $HOME/my-o3de-projects/o3de-multiplayersample-assets/Gems
$HOME/o3de/scripts/o3de register -p $HOME/my-o3de-projects/o3de-multiplayersample

Executing any of these commands results in o3de/scripts/o3de: Is a directory information shown inside the Terminal window. To register the Editor, the Project and Gems the User has to add the .sh extension to mentioned commands:

$HOME/o3de/scripts/o3de.sh register --this-engine
$HOME/o3de/scripts/o3de.sh register --all-gems-path $HOME/my-o3de-projects/o3de-multiplayersample-assets/Gems
$HOME/o3de/scripts/o3de.sh register -p $HOME/my-o3de-projects/o3de-multiplayersample

Please refer to the attached screenshot for more information.

This issue should be considered as Major.

Steps to reproduce
Steps to reproduce the behavior:

1. Go to https://github.com/o3de/o3de-multiplayersample/blob/development/README_LINUX.md
2. Follow the instruction to Step 2. Register the engine, the project, and the Gems
3. Execute commands provided in the documentation.
4. Add the .sh extension to commands.

Expected behavior
MultiplayerSample Project README_LINUX.md provides correct commands for register the Editor, the Project and Gems.

Actual behavior
MultiplayerSample Project README_LINUX.md provides incorrect commands to register the Editor, the Project and Gems.

**Screen

Found in Branch
Development (47b9ab3)

Desktop/Device:

• Device: PC
• OS: Ubuntu
• Version: 20.04
• CPU: AMD Ryzen 7 3800X 8-Core Processor
• GPU: AMD Radeon RX 5700 XT
• Memory: 16 GB

[AMZN-Gene]

Nice find! Yeah, docs should be updated to include the .sh