message: add -Zmiri-disable-data-race-detector to readme
diff: @@ -198,6 +198,8 @@ environment variable:
  * `-Zmiri-disable-alignment-check` disables checking pointer alignment, so you
  can focus on other failures, but it means Miri can miss bugs in your program.
  Using this flag is **unsound**.
  +* `-Zmiri-disable-data-race-detector` disables checking for data races. Using
  + this flag is **unsound**.
  * `-Zmiri-disable-stacked-borrows` disables checking the experimental
  [Stacked Borrows] aliasing rules. This can make Miri run faster, but it also
  means no aliasing violations will be detected. Using this flag is **unsound**
  