Add the conceal patch from Vince Negri.
diff --git a/runtime/doc/various.txt b/runtime/doc/various.txt
index 3f1d061..63b279b 100644
--- a/runtime/doc/various.txt
+++ b/runtime/doc/various.txt
@@ -293,8 +293,10 @@
N *+cmdline_hist* command line history |cmdline-history|
N *+cmdline_info* |'showcmd'| and |'ruler'|
N *+comments* |'comments'| support
+m *+conceal* "conceal" support, see ||conceal|| |:syn-conceal| etc.
N *+cryptv* encryption support |encryption|
B *+cscope* |cscope| support
+m *+cursorbind* |'cursorbind'| support
m *+cursorshape* |termcap-cursor-shape| support
m *+debug* Compiled for debugging.
N *+dialog_gui* Support for |:confirm| with GUI dialog.