Update downloading to pulling in api.md (#11170)

update api.md to make it consist with code.
https://github.com/ollama/ollama/blob/main/server/download.go#L447

docs/api.md

@@ -1593,7 +1593,7 @@ Then there is a series of downloading responses. Until any of the download is co
 
 ```json
 {
-  "status": "downloading digestname",
+  "status": "pulling digestname",
   "digest": "digestname",
   "total": 2142590208,
   "completed": 241970