Update INSTALL-cloud.md (#23624)

Adding Tutorial for installation Docker and Git,

docs/INSTALL-cloud.md

@@ -75,7 +75,12 @@ Connect to your server via its IP address using SSH, or [Putty][put] on Windows:
 
 Either use the root password from the email DigitalOcean sent you when the server was set up, or have a valid SSH key configured on your local machine.
 
-### 5. Install Discourse
+### 5. Install Prerequisites for Docker (Debian/ Ubunto basted Distro example)
+
+    sudo apt install docker.io
+    sudo apt install git
+
+### 6. Install Discourse
 
 Clone the [Official Discourse Docker Image][dd] into `/var/discourse`.
 
@@ -86,7 +91,7 @@ Clone the [Official Discourse Docker Image][dd] into `/var/discourse`.
 
 You will need to be root through the rest of the setup and bootstrap process.
 
-### 6. Edit Discourse Configuration
+### 7. Edit Discourse Configuration
 
 Launch the setup tool at
 
@@ -109,13 +114,13 @@ Let's Encrypt account setup is to give you a free HTTPS certificate for your sit
 
 This will generate an `app.yml` configuration file on your behalf, and then kicks off bootstrap. Bootstrapping takes between **2-8 minutes** to set up your Discourse. If you need to change these settings after bootstrapping, you can run `./discourse-setup` again (it will re-use your previous values from the file) or edit `/containers/app.yml` manually with `nano` and then `./launcher rebuild app`, otherwise your changes will not take effect.
 
-### 7. Start Discourse
+### 8. Start Discourse
 
  Once bootstrapping is complete, your Discourse should be accessible in your web browser via the domain name `discourse.example.com` you entered earlier.
 
 <img src="https://www.discourse.org/images/install/17/discourse-congrats.png" width="650">
 
-### 8. Register New Account and Become Admin
+### 9. Register New Account and Become Admin
 
 Register a new admin account using one of the email addresses you entered before bootstrapping.
 
@@ -133,7 +138,7 @@ After completing the setup wizard, you should see Staff topics and **READ ME FIR
 
 <img src="https://www.discourse.org/images/install/17/discourse-homepage.png">
 
-### 9. Post-Install Maintenance
+### 10. Post-Install Maintenance
 
 - We strongly suggest you turn on automatic security updates for your OS. In Ubuntu use the `dpkg-reconfigure -plow unattended-upgrades` command. In CentOS/RHEL, use the [`yum-cron`](https://www.redhat.com/sysadmin/using-yum-cron) package.
 - If you are using a password and not a SSH key, be sure to enforce a strong root password. In Ubuntu use the `apt install libpam-cracklib` package. We also recommend `fail2ban` which blocks any IP addresses for 10 minutes that attempt more than 3 password retries.
@@ -173,7 +178,7 @@ Options:
     --docker-args              Extra arguments to pass when running docker
 ```
 
-### 10. (Optional) Add More Discourse Features
+### 11. (Optional) Add More Discourse Features
 
 Do you want...