Merge pull request kaytu-io#273 from kaytu-io/fix-gcp-document

fix: add document for gcp usage

docs/how-to-gcp.md

@@ -0,0 +1,32 @@
+This document explains how to optimize gcp compute instances
+
+## 1. Have the following Software Installed
+
+1.  Kaytu CLI
+
+
+## 2. Login to kaytu CLI
+`kaytu login`
+
+Install CLI plugin:
+
+    kaytu plugin install gcp
+
+
+## 4. Create a Service Account
+
+Create a service account with the following roles:
+1. Cloud Billing
+2. Compute Engine 
+
+## 5. Create Key and store credentials file
+
+## 6. Export credentials file path
+
+Export credentials file path in the environment variable
+
+    export GOOGLE_APPLICATION_CREDENTIALS="/path/to/credentials.json"
+
+## 7. Run optimization Check
+
+> kaytu optimize compute-instance