Adds --emit to --help output. (#1484)

* Adds --emit to --help output.

* Add backticks, because Andrew is impossible to please.

* Removed formatting change introduced by a different version of prettier.

src/bin.ts

@@ -158,6 +158,7 @@ export function main(
     --pretty                        Use pretty diagnostic formatter (usually enabled by default)
     --skip-project                  Skip reading \`tsconfig.json\`
     --skip-ignore                   Skip \`--ignore\` checks
+    --emit                          Emit output files into \`.ts-node\` directory
     --scope                         Scope compiler to files within \`scopeDir\`.  Anything outside this directory is ignored.
     --scope-dir                     Directory for \`--scope\`
     --prefer-ts-exts                Prefer importing TypeScript files over JavaScript files