Add note about Alpine locales

postgres/content.md

@@ -169,7 +169,7 @@ There are many ways to set PostgreSQL server configuration. For information on w
 
 ## Locale Customization
 
-You can extend the image with a simple `Dockerfile` to set a different locale. The following example will set the default locale to `de_DE.utf8`:
+You can extend the Debian-based images with a simple `Dockerfile` to set a different locale. The following example will set the default locale to `de_DE.utf8`:
 
 ```dockerfile
 FROM %%IMAGE%%:9.4
@@ -179,6 +179,8 @@ ENV LANG de_DE.utf8
 
 Since database initialization only happens on container startup, this allows us to set the language before it is created.
 
+Also of note, Alpine-based variants do *not* support locales; see ["Character sets and locale" in the musl documentation](https://wiki.musl-libc.org/functional-differences-from-glibc.html#Character-sets-and-locale) for more details.
+
 ## Additional Extensions
 
 When using the default (Debian-based) variants, installing additional extensions (such as PostGIS) should be as simple as installing the relevant packages (see [github.com/postgis/docker-postgis](https://github.com/postgis/docker-postgis/blob/4eb614133d6aa87bfc5c952d24b7eb1f499e5c7c/12-3.0/Dockerfile) for a concrete example).