Docs-15210 v5.0 (#973)

* DOCS-15210 add readConcern mention

* writeConcern -> write concern

* CR 1 Feedback

* update verbiage

* remove duplicate your

* remove ref

* update

Author: ianf-mongodb

source/includes/fact-psa-performance-issues.rst

@@ -1,5 +1,11 @@
-If you are using a three-member primary-secondary-arbiter (PSA)
-architecture, the write concern :writeconcern:`"majority"` can cause
-performance issues if a secondary is unavailable or lagging. See
-:ref:`performance-issues-psa` for advice on how to mitigate these
-issues.
+If you are using a three-member primary-secondary-arbiter (PSA) 
+architecture, consider the following: 
+
+- The write concern :writeconcern:`"majority"` can cause
+  performance issues if a secondary is unavailable or lagging. For
+  advice on how to mitigate these issues, see 
+  :ref:`performance-issues-psa`.
+
+- If you are using a global default :readconcern:`"majority"` 
+  and the write concern is less than the size of the majority,
+  your queries may return stale (not fully replicated) data.