Document known issue for restore pane contents feature

docs/restoring_pane_contents.md

@@ -5,3 +5,27 @@ This plugin enables saving and restoring tmux pane contents.
 This feature can be enabled by adding this line to `.tmux.conf`:
 
     set -g @resurrect-capture-pane-contents 'on'
+
+##### Known issue
+
+When using this feature, please check the value of `default-command`
+tmux option. That can be done with `$ tmux show -g default-command`.
+
+The value should NOT contain `&&` or `||` operators. If it does, simplify the
+option so those operators are removed.
+
+Example:
+
+- this will cause issues (notice the `&&` and `||` operators):
+
+        set -g default-command "which reattach-to-user-namespace > /dev/null && reattach-to-user-namespace -l $SHELL || $SHELL -l"
+
+- this is ok:
+
+        set -g default-command "reattach-to-user-namespace -l $SHELL"
+
+Related [bug](https://github.com/tmux-plugins/tmux-resurrect/issues/98).
+
+Alternatively, you can let
+[tmux-sensible](https://github.com/tmux-plugins/tmux-sensible)
+handle this option in a cross-platform way and you'll have no problems.