Update xreadgroup.md to clarify entry deletion (#2412)

* Update xreadgroup.md to clarify entry deletion

Clarify the conditions under which entries can be deleted from the stream, including trimming and explicit deletion commands.

* Fix formatting and punctuation in xreadgroup.md

* Update content/commands/xreadgroup.md

---------

Co-authored-by: David Dougherty <[email protected]>

Author: LiorKogan

content/commands/xreadgroup.md

@@ -232,8 +232,12 @@ To see how the command actually replies, please check the [`XREAD`]({{< relref "
 
 ## What happens when a pending message is deleted?
 
-Entries may be deleted from the stream due to trimming or explicit calls to [`XDEL`]({{< relref "/commands/xdel" >}}) at any time.
-By design, Redis doesn't prevent the deletion of entries that are present in the stream's PELs.
+Entries may be deleted from the stream due to trimming with [`XADD`]({{< relref "/commands/xall" >}}) or [`XTRIM`]({{< relref "/commands/xtrim" >}}),
+or explicit calls to [`XDEL`]({{< relref "/commands/xdel" >}}), [`XDELEX`]({{< relref "/commands/xdelex" >}}), or [`XACKDEL`]({{< relref "/commands/xackdel" >}}).
+
+When an entry is trimmed with [`XADD`]({{< relref "/commands/xall" >}}) or [`XTRIM`]({{< relref "/commands/xtrim" >}}) and `DELREF` or `ACKED` are not specified,
+deleted with [`XDEL`]({{< relref "/commands/xdel" >}}), or deleted with [`XDELEX`]({{< relref "/commands/xdelex" >}}) or [`XACKDEL`]({{< relref "/commands/xackdel" >}}) 
+and `DELREF` or `ACKED` are not specified, Redis doesn't prevent the deletion of entries that are present in the stream's PELs.
 When this happens, the PELs retain the deleted entries' IDs, but the actual entry payload is no longer available.
 Therefore, when reading such PEL entries, Redis will return a null value in place of their respective data.