gcloud-init: add page (#11626)

Co-authored-by: Juri Dispan <juri.dispan@posteo.net>
Co-authored-by: Lena <126529524+acuteenvy@users.noreply.github.com>

pages/common/gcloud-init.md

@@ -0,0 +1,16 @@
+# gcloud init
+
+> Launch an interactive workflow to setup `gcloud` or reinitialize configurations.
+> More information: <https://cloud.google.com/sdk/gcloud/reference/init>.
+
+- Launch a "Getting Started" workflow:
+
+`gcloud init`
+
+- Launch a workflow without diagnostics:
+
+`gcloud init --skip-diagnostics`
+
+- Use the console for authentication:
+
+`gcloud init --console-only`