Fix spelling of --enable-tor2web-mode in manpage

Fixes bug 19153; patch from "U+039b", who is apparently an uppercase
lambda?

changes/bug19153

+  o Documentation:
+    - Fix spelling of "--enable-tor2web-mode" in the manpage. Closes
+      ticket #19153. Patch from "U+039b".

doc/tor.1.txt

@@ -1426,7 +1426,7 @@ The following options are useful only for clients (that is, if
     **non-anonymously**.  This option also disables client connections to
     non-hidden-service hostnames through Tor. It **must only** be used when
     running a tor2web Hidden Service web proxy.
-    To enable this option the compile time flag --enable-tor2webmode must be
+    To enable this option the compile time flag --enable-tor2web-mode must be
     specified. (Default: 0)
 
 [[Tor2webRendezvousPoints]] **Tor2webRendezvousPoints** __node__,__node__,__...__::