message: Document string values for LTO
diff: @@ -294,7 +294,9 @@ rpath = false # controls whether compiler should set loader paths.
  # If true, passes `-C rpath` flag to the compiler.
  lto = false # Link Time Optimization usually reduces size of binaries
  # and static libraries. Increases compilation time.
  - # If true, passes `-C lto` flag to the compiler.
  + # If true, passes `-C lto` flag to the compiler, and if a
  + # string is specified like 'thin' then `-C lto=thin` will
  + # be passed
  debug-assertions = true # controls whether debug assertions are enabled
  # (e.g. debug_assert!() and arithmetic overflow checks)
  codegen-units = 1 # if > 1 enables parallel code generation which improves
  