Maybe also document condition-function.

DOC.md

@@ -61,6 +61,12 @@ The second argument to `s` is a table containing all nodes that belong to the
 snippet. If the table only has a single node, it can be passed directly
 without wrapping it in a table.
 
+The third argument is the condition-function. The snippet will be expanded only
+if it returns true (default is a function that just returns true).
+
+The fourth and following args are passed to the condition-function(allows
+reusing condition-functions).
+
 Snippets contain some interesting tables, eg. `snippet.env` contains variables
 used in the LSP-protocol like `TM_CURRENT_LINE` or `TM_FILENAME` or
 `snippet.captures`, where capture-groups of regex-triggers are stored. These