note on naming restrictions (#2625)

* note on naming restrictions

else push would fail with cryptic
retrieving manifest 
Error: file does not exist
==> maybe change that in code too

* Update docs/import.md

---------
Co-authored-by: C-4-5-3 <154636388+C-4-5-3@users.noreply.github.com>
Co-authored-by: Jeffrey Morgan <jmorganca@gmail.com>

docs/import.md

@@ -136,6 +136,8 @@ Next, copy your model to your username's namespace:
 ollama cp example <your username>/example
 ```
 
+> Note: model names may only contain lowercase letters, digits, and the characters `.`, `-`, and `_`.
+
 Then push the model:
 
 ```