doc: jlink: update to 8.42

Updated shortcuts.txt to list J-Link 8.42.
NRFU-1559.

Signed-off-by: Grzegorz Ferenc <[email protected]>

Author: greg-fer

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -33,7 +33,7 @@ The following sections provide detailed lists of changes by component.
 IDE, OS, and tool support
 =========================
 
-|no_changes_yet_note|
+* Updated the required `SEGGER J-Link`_ version to v8.42.
 
 Board support
 =============

doc/nrf/shortcuts.txt

@@ -6,7 +6,7 @@
 .. |release_tt| replace:: ``v3.0.0``
 .. |release_number_tt| replace:: ``3.0.0``
 
-.. |jlink_ver| replace:: v8.18
+.. |jlink_ver| replace:: v8.42
 
 .. ### Config shortcuts