Add missing sidebar link to std.net.curl docs

std.ddoc

@@ -229,6 +229,7 @@ NAVIGATION_PHOBOS=
 	$(LI <a href="std_c_string.html" title="Strings">std.c.string</a>)
 	$(LI <a href="std_c_time.html" title="Time">std.c.time</a>)
 	$(LI <a href="std_c_wcharh.html" title="Wide characters">std.c.wcharh</a>)
+	$(LI <a href="std_net_curl.html" title="High level curl wrapper">std.net.curl</a>)
 	$(LI <a href="std_net_isemail.html" title="Validate e-mail addresses">std.net.isemail</a>)
 	$(LI <a href="std_windows_charset.html" title="Conversion to/from Windows character sets">std.windows.charset</a>)
 	$(LI <a href="index.html#std_windows" title="Modules specific to Windows">std.windows</a>)