Doc: fix typo (#277)

Author: jimt

doc/admin/install/google_cloud.md

@@ -13,7 +13,7 @@ If you're just starting out, we recommend [installing code-server locally](../..
 - Choose an appropriate machine type (we recommend 2 vCPU and 7.5 GB RAM, more depending on team size and number of repositories/languages enabled)
 - Choose Ubuntu 16.04 LTS as your boot disk
 - Check the boxes for **Allow HTTP traffic** and **Allow HTTPS traffic** in the **Firewall** section
-- Create your VM, and **take note** of it's public IP address.
+- Create your VM, and **take note** of its public IP address.
 - Copy the link to download the latest Linux binary from our [releases page](https://github.com/codercom/code-server/releases)
 
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