profile.d: add instructions how to deactivate 80-systemd-osc-context.sh

This was requested in https://github.com/systemd/systemd/issues/42333.
Indeed, this integration is using three levels of systemd magick, so
doing this correctly is not obvious. Let's include specific instructions
to help people for whom this integration is causing problems.

profile.d/70-systemd-shell-extra.sh

@@ -12,6 +12,15 @@
 # credentials shell.prompt.prefix, shell.prompt.suffix and shell.welcome, and
 # are propagated into these environment variables by pam_systemd(8).
 
+# This file is "activated" through systemd-tmpfiles which links it into
+# /etc/profile.d/. To disable this, remove the
+# /etc/profile.d/70-systemd-shell-extra.sh symlink and mask the
+# 20-systemd-shell-extra.conf snippet (as root):
+#
+#   test -h /etc/profile.d/70-systemd-shell-extra.sh && \
+#     rm -v /etc/profile.d/70-systemd-shell-extra.sh && \
+#     ln -s /dev/null /etc/tmpfiles.d/20-systemd-shell-extra.conf
+
 if [ -n "${SHELL_PROMPT_PREFIX-}" ]; then
     if [ -n "${BASH_VERSION-}" ] && [ "$PS1" = "\\s-\\v\\\$ " ]; then
         PS1="[\u@\h \W]\\$ "

profile.d/80-systemd-osc-context.sh

@@ -14,6 +14,15 @@
 # specification for the shell prompt. For details see:
 # https://uapi-group.org/specifications/specs/osc_context/
 
+# This file is "activated" through systemd-tmpfiles which links it into
+# /etc/profile.d/. To disable this, remove the
+# /etc/profile.d/80-systemd-osc-context.sh symlink and mask the
+# 20-systemd-osc-context.conf snippet (as root):
+#
+#   test -h /etc/profile.d/80-systemd-osc-context.sh && \
+#     rm -v /etc/profile.d/80-systemd-osc-context.sh && \
+#     ln -s /dev/null /etc/tmpfiles.d/20-systemd-osc-context.conf
+
 # Not bash?
 [ -n "${BASH_VERSION:-}" ] || return 0