gcloud-*: add pages (#11625)

* gcloud-*: add pages

---------

Signed-off-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>
Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>
Co-authored-by: Sebastiaan Speck <12570668+sebastiaanspeck@users.noreply.github.com>
Co-authored-by: Starbeamrainbowlabs <sbrl@starbeamrainbowlabs.com>

pages/common/gcloud-topic.md

@@ -0,0 +1,13 @@
+# gcloud topic
+
+> Provides supplementary help for topics not directly associated with individual commands. See also `gcloud`.
+> For general help, see `tldr gcloud help`.
+> More information: <https://cloud.google.com/sdk/gcloud/reference/topic>.
+
+- View supplementary help material for non-command topics like accessibility, filtering, and formatting:
+
+`gcloud topic {{topic_name}}`
+
+- List all available topics:
+
+`gcloud topic --help`