New rule proposal: Avoid commented-out lines of code

Description

Commented-out lines should be removed before release. It might already be broken.
If old code is later required again, it will be available in source code management system.

See also:

• Robert C. Martin's Clean Code Tip of the Week #7: Clean up Old Commented Out Code
• Can commented-out code be valuable documentation?

Expected behavior

Report any commented-out code.

• Report multi-line commented code

let animal = "bird"

// Test the length of the string.
if (animal.Length = 1) then
    // Not reached.
    printfn "A"
(*
elif (animal.Length = 2) then
    // Not reached.
    printfn "B"
*)
else
    // This statement is reached.
    printfn "C"

• Report single line commented code

assignment.
let result =
    if count >= 200 then 1
    // elif count <= 100 then 2
    else 3

Actual behavior

Rule not available today.

Known workarounds

One might configure a hint

Related information

Rule not listed at http://fsprojects.github.io/FSharpLint/Rules.html

Start with the two F# examples in the issue and review how existing rules are documented, including the linked rules page. Done means the linter reports both multi-line and single-line commented-out code, and the new rule is listed among the available rules.