FSharpStyleGuide: discourage task{} blocks

Author: knocte

FSharpStyleGuide.md

@@ -121,6 +121,8 @@ developer to use a type-less style of catching an exception, plus the
 discriminated union used for its result is quite unreadable (`Choice1Of2`
 and `Choice2Of2` don't give any clue about which one is the successful case
 and which one is the exceptional one).
+* We prefer `async{}` blocks better than `task{}` ones because the former is
+idiomatic F#.
 * When using the function `ignore`, use always the generic type (`ignore<'T>`).
 * Do not use `System.ParamArray` (for variable number of arguments) as it's
 easy to shoot yourself in the foot, and is not idiomatic F# (it was meant for