Added official Google Cloud instructions for building firebase on Cloud Build to ReadMe (#453)
Added official Google Cloud instructions for building firebase on Cloud Build to ReadMe (#453)

* Update README.md

* Formatted steps

* Fixed typo

* Removed extra space

* Removed word 'steps' from README additions

* Renamed new section title

* Fixed typo

* Removed `#` header in Markdown

* Rearranged sentences
GoogleCloudPlatform/cloud-builders-community,GoogleCloudPlatform/cloud-builders-community,GoogleCloudPlatform/cloud-builders-community,GoogleCloudPlatform/cloud-builders-community,GoogleCloudPlatform/cloud-builders-community,GoogleCloudPlatform/cloud-builders-community,GoogleCloudPlatform/cloud-builders-community,GoogleCloudPlatform/cloud-builders-community