fix(DB/Commands): Fix typo in wp show command description. (#16591)

* This adds a SQL `UPDATE` command which fixes a typo present in the `wp show` command help text.

`s/$slected__waypoint/$selected_waypoint`

---

Previously:

`Syntax: .wp show $option
Options:
on $pathid (or selected creature with loaded path) - Show path
off - Hide path
info $selected_waypoint - Show info for selected waypoint.`
``

* Fix SQL Codestyle in `command_typo_fix.sql`

This change changes the format of the SQL query to be easier to read.

Additionally uses a variable to improve the readability of the actual UPDATE query, due the length of the help text string.

data/sql/updates/pending_db_world/command_typo_fix.sql

@@ -0,0 +1,3 @@
+
+SET @HELP_TEXT := 'Syntax: .wp show $option\nOptions:\non $pathid (or selected creature with loaded path) - Show path\noff - Hide path\ninfo $selected_waypoint - Show info for selected waypoint.';
+UPDATE `command` SET `help` = @HELP_TEXT WHERE `name` = 'wp show';