CLDR-17177 kbd: update per feedback

- fixed "spacing mark" typo

docs/ldml/tr35-keyboards.md

@@ -1500,7 +1500,7 @@ _Attribute:_ `id` (required)
 
 _Attribute:_ `value` (required)
 
-> Strings may contain whitespaces. However, for clarity, it is recommended to escape spacing marks, even in strings.
+> Strings may contain whitespaces. However, for clarity, it is recommended to escape non-spacing marks, even in strings.
 > This attribute may be escaped with `\u` notation, see [Escaping](#escaping).
 > Variables may refer to other string variables if they have been previously defined, using `${string}` syntax.
 > [Markers](#markers) may be included with the `\m{…}` notation.