Update tooling-syntax-rewriting.md

[csgn]

I checked scalac command options as follows:

$ scalac --help
 -javaextdirs  Override java extdirs classpath.
    -language  Enable one or more language features.
  -new-syntax  Require `then` and `do` in control expressions.
   **-no-indent  Require classical {...} syntax, indentation is not significant.**
   -nowarn  Silence all warnings.

But in docs wrote as -noindent. So I change it to -no-indent