clarify

docs/libcurl/curl_multi_remove_handle.3

@@ -14,6 +14,9 @@ specified easy handle be removed from this multi handle's control.
 
 When the easy handle has been removed from a multi stack, it is again
 perfectly legal to invoke \fIcurl_easy_perform()\fP on this easy handle.
+
+Removing a handle while being used, will effectively halt all transfers in
+progress.
 .SH RETURN VALUE
 CURLMcode type, general libcurl multi interface error code.
 .SH "SEE ALSO"