corrected minetest.pos_to_string()

corrected this bit reflect the function properly.

doc/lua_api.txt

@@ -1715,8 +1715,9 @@ Helper functions
     * e.g. `string:split("a,b", ",") == {"a","b"}`
 * `string:trim()`
     * e.g. `string.trim("\n \t\tfoo bar\t ") == "foo bar"`
-* `minetest.pos_to_string({x=X,y=Y,z=Z})`: returns `"(X,Y,Z)"`
+* `minetest.pos_to_string({x=X,y=Y,z=Z}, decimal_places))`: returns `"(X,Y,Z)"`
     * Convert position to a printable string
+      Optional: 'decimal_places' will round the x, y and z of the pos to the given decimal place.
 * `minetest.string_to_pos(string)`: returns a position
     * Same but in reverse. Returns `nil` if the string can't be parsed to a position.
 * `minetest.string_to_area("(X1, Y1, Z1) (X2, Y2, Z2)")`: returns two positions