Update installation documentation for version 0.27.0.
Update installation documentation for version 0.27.0.

Signed-off-by: Bjorn Leffler <d706fb27584989447a08f9d2609497488b760f7c@google.com>

GoogleCloudPlatform/gcsfuse,GoogleCloudPlatform/gcsfuse,GoogleCloudPlatform/gcsfuse