message: Remove statement that opt-level 0 turns on debug
  See
diff: @@ -41,7 +41,7 @@ rearrange the compiled code which may make it harder to use with a debugger.
  The valid options are:
  -* `0`: no optimizations, also turns on [`cfg(debug_assertions)`](#debug-assertions).
  +* `0`: no optimizations
  * `1`: basic optimizations
  * `2`: some optimizations
  * `3`: all optimizations
  