Reflect the fact that this is a "Lexer for various shells" as described in the top comment, and not just a Lexer for Bash.

Bash is not shell, it is definitely a more advanced language, with array support, better loops, the `function` keyword, the `select` command, file slurping, more expansions, more conditionals, etc.

Assuming that any shell script would be a "Bash script" is error inducing at best, novices might try, not knowing better, to introduce so called bashisms in a POSIX shell script, and even seasoned developers might be mislead and assume the wrong thing.

Calling it a "Shell" script costs nothing, is correct, and will prevent any such issues.