feat: add -yflag alias for download command

Author: fspoettel

README.md

@@ -69,7 +69,7 @@ cargo download <day>
 # 🎄 Successfully wrote input to "src/inputs/01.txt"!
 ```
 
-To download inputs for previous years, append the `--year` flag. _(example: `cargo download 1 --year 2020`)_
+To download inputs for previous years, append the `--year/-y` flag. _(example: `cargo download 1 --year 2020`)_
 
 Puzzle inputs are not checked into git. [Reasoning](https://old.reddit.com/r/adventofcode/comments/k99rod/sharing_input_data_were_we_requested_not_to/gf2ukkf/?context=3).
 

src/bin/download.rs

@@ -12,7 +12,7 @@ fn parse_args() -> Result<Args, pico_args::Error> {
     let mut args = pico_args::Arguments::from_env();
     Ok(Args {
         day: args.free_from_str()?,
-        year: args.opt_value_from_str("--year")?,
+        year: args.opt_value_from_str(["-y", "--year"])?,
     })
 }