libcurl-multi.3: update the list of areas still blocking

docs/libcurl/libcurl-multi.3

@@ -142,8 +142,7 @@ multi interface. While we certainly want and intend for these to get fixed in
 the future, you should be aware of the following current restrictions:
 
 .nf
- - Name resolves on non-windows unless c-ares is used
- - GnuTLS SSL connections
+ - Name resolves unless the c-ares or threaded-resolver backends are used
  - NSS SSL connections
  - Active FTP connections
  - HTTP proxy CONNECT operations