doc: west: v0.6.2 fixes a critical v0.6.1 bug

All v0.6.1 users must upgrade. Add release notes blurb.

Signed-off-by: Marti Bolivar <[email protected]>

Author: mbolivar-nordic

doc/guides/west/release-notes.rst

@@ -1,9 +1,21 @@
 West Release Notes
 ##################
 
+v0.6.2
+******
+
+This point release fixes an error in the behavior of ``west
+update --fetch=smart``, introduced in v0.6.1.
+
+All v0.6.1 users must upgrade.
+
 v0.6.1
 ******
 
+.. warning::
+
+   Do not use this point release. Make sure to use v0.6.2 instead.
+
 The user-visible features in this point release are:
 
 - The `west update <west-multi-repo-cmds>` command has a new ``--fetch``