Properly escape Markdown markups at minetest.string_to_area (#14774)

Co-authored-by: DS <ds.desour@proton.me>

doc/lua_api.md

@@ -4007,8 +4007,9 @@ Helper functions
     * X1, Y1, ... Z2 are coordinates
     * `relative_to`: Optional. If set to a position, each coordinate
       can use the tilde notation for relative positions
-    * Tilde notation: "~": Relative coordinate
-                      "~<number>": Relative coordinate plus <number>
+    * Tilde notation
+      * `"~"`: Relative coordinate
+      * `"~<number>"`: Relative coordinate plus `<number>`
     * Example: `minetest.string_to_area("(1,2,3) (~5,~-5,~)", {x=10,y=10,z=10})`
       returns `{x=1,y=2,z=3}, {x=15,y=5,z=10}`
 * `minetest.formspec_escape(string)`: returns a string