docs(commander): detail about sinks.input

golibs/commander/commander.go

@@ -17,8 +17,11 @@ In this example, a command with the name of `hello` is created
 that will print `Hello world!` to output. One question you may
 have is: What is the `sinks` parameter?
 
-The `sinks` parameter is a table with 3 keys: `in`, `out`,
+The `sinks` parameter is a table with 3 keys: `input`, `out`, and `err`.
-and `err`. All of them are a @Sink.
+There is an `in` alias to `input`, but it requires using the string accessor syntax (`sinks['in']`)
+as `in` is also a Lua keyword, so `input` is preferred for use.
+All of them are a @Sink.
+In the future, `sinks.in` will be removed.
 
 - `in` is the standard input.
 You may use the read functions on this sink to get input from the user.