Add note about glossaries

Author: Lucas Mathis

docs/getting-started/supported-languages.mdx

@@ -125,7 +125,7 @@ If trying to convert between variants of the same language (e.g. `EN-US` to `EN-
 - `ZH` - Chinese _(all Chinese variants)_
 - `ZU` - Zulu*
 
-\* These languages only work with the `quality_optimized` model or when no model is specified. They are not compatible with requests that specify the `latency_optimized` model.
+\* These languages only work with the `quality_optimized` model or when no model is specified. They are not compatible with requests that specify the `latency_optimized` model. These languages do not support glossaries or formality.
 
 ### Translation target languages
 
@@ -251,7 +251,7 @@ If trying to convert between variants of the same language (e.g. `EN-US` to `EN-
 - `ZH-HANT` - Chinese (traditional)
 - `ZU` - Zulu*
 
-\* These languages only work with the `quality_optimized` model or when no model is specified. They are not compatible with requests that specify the `latency_optimized` model.
+\* These languages only work with the `quality_optimized` model or when no model is specified. They are not compatible with requests that specify the `latency_optimized` model. These languages do not support glossaries or formality.
 
 ### Text improvement languages (DeepL API for Write)