[synthetics] Document private locations space awareness (#4873) (#4893)

* document private locations space awareness

* read @mdbirnstiehl's mind before he even reviews

(cherry picked from commit b599ea8)

Co-authored-by: Colleen McGinnis <[email protected]>

Author: mergify[bot]

docs/en/observability/synthetics-private-location.asciidoc

@@ -147,8 +147,11 @@ When the {agent} is running you can add a new {private-location} in {kib}:
 . Find `Synthetics` in the {kibana-ref}/introduction.html#kibana-navigation-search[global search field].
 . Click **Settings**.
 . Click **{private-location}s**.
-. Click **Add location**.
-. Give your new location a unique _Location name_ and select the _Agent policy_ you created above.
+. Click **Create location**.
+. Give your new location a unique _Location name_.
+. Select the _Agent policy_ you created above.
+. (Optional) In _Tags_, select {kibana-ref}/managing-tags.html[tags] to assign to this location.
+. (Optional) In _Spaces_, specify the {kibana-ref}/xpack-spaces.html[spaces] where this location will be available.
 . Click **Save**.
 
 IMPORTANT: It is not currently possible to use custom CAs for synthetics browser tests in private locations without following a workaround. To learn more about the workaround, refer to the following GitHub issue: https://github.com/elastic/synthetics/issues/717[elastic/synthetics#717].