Fix '--release' flag place in man page's example

'crystal --release build some_program.cr' does not work.

Author: makenowjust

man/crystal.1

@@ -44,8 +44,8 @@ Note that by default the generated executables are not fully optimized.
 To turn optimizations on, use the --release flag:
 .Bd -offset indent-two
 .Nm
---release
 build
+--release
 some_program.cr
 .Ed