patch 8.0.1295: cannot automatically get a server name in a terminal

Problem:    Cannot automatically get a server name in a terminal.
Solution:   Add the --enable-autoservername flag to configure. (Cimbali,
            closes #2317)
diff --git a/runtime/doc/various.txt b/runtime/doc/various.txt
index d994e71..07ec3b1 100644
--- a/runtime/doc/various.txt
+++ b/runtime/doc/various.txt
@@ -309,6 +309,7 @@
    *+ARP*		Amiga only: ARP support included
 B  *+arabic*		|Arabic| language support
 N  *+autocmd*		|:autocmd|, automatic commands
+H  *+autoservername*	Automatically enable |clientserver|
 m  *+balloon_eval*	|balloon-eval| support. Included when compiling with
 			supported GUI (Motif, GTK, GUI) and either
 			Netbeans/Sun Workshop integration or |+eval| feature.