grep-cli: support Brotli/Zstd decompression

Fixes #1099

src/app.rs

@@ -2021,9 +2021,9 @@ This flag can be used with the -o/--only-matching flag.
 fn flag_search_zip(args: &mut Vec<RGArg>) {
     const SHORT: &str = "Search in compressed files.";
     const LONG: &str = long!("\
-Search in compressed files. Currently gz, bz2, xz, lzma and lz4 files are
-supported. This option expects the decompression binaries to be available in
-your PATH.
+Search in compressed files. Currently gzip, bzip2, xz, LZ4, LZMA, Brotli and
+Zstd files are supported. This option expects the decompression binaries to be
+available in your PATH.
 
 This flag can be disabled with --no-search-zip.
 ");