Document "--rate-limit" as alternative form for "--limit-rate" option

[pixelrust]

Checklist

• I'm reporting a broken site support issue
• I've verified that I'm running youtube-dl version 2020.09.20
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar bug reports including closed ones
• I've read bugs section in FAQ

Verbose log

$ youtube-dl -v --limit-rate=600K https://vimeo.com/375957610
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'--limit-rate=600K', u'https://vimeo.com/375957610']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2020.09.20
[debug] Python version 2.7.18 (CPython) - Linux-5.4.0-52-lowlatency-x86_64-with-Ubuntu-20.04-focal
[debug] exe versions: ffmpeg 4.2.4, ffprobe 4.2.4
[debug] Proxy map: {}
[vimeo] 375957610: Downloading webpage
[vimeo] 375957610: Extracting information
[vimeo] 375957610: Downloading JSON metadata
[vimeo] 375957610: Downloading JSON metadata
[vimeo] 375957610: Checking Original video URL
[vimeo] 375957610: Downloading akfire_interconnect_quic m3u8 information
[vimeo] 375957610: Downloading akfire_interconnect_quic m3u8 information
[vimeo] 375957610: Downloading fastly_skyfire m3u8 information
[vimeo] 375957610: Downloading fastly_skyfire m3u8 information
[vimeo] 375957610: Downloading akfire_interconnect_quic MPD information
[vimeo] 375957610: Downloading akfire_interconnect_quic MPD information
[vimeo] 375957610: Downloading fastly_skyfire MPD information
[vimeo] 375957610: Downloading fastly_skyfire MPD information
[debug] Default format spec: bestvideo+bestaudio/best
[debug] Invoking downloader on u'https://skyfire.vimeocdn.com/1603213192-0xd59bafbc9efd5fcd7eb844a4880e9b6e8cecc3c6/89d05963-15ae-4baa-bff5-14becc915426/sep/video/e4e3bf25/playlist.m3u8'
[hlsnative] Downloading m3u8 manifest
[hlsnative] Total fragments: 80
[download] Destination: My Expanded View-375957610.fhls-fastly_skyfire_sep-5233.mp4
[download]   1.5% of ~74.04MiB at 598.69KiB/s ETA 02:38^C

$ youtube-dl -v --rate-limit=600K https://vimeo.com/375957610
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'--rate-limit=600K', u'https://vimeo.com/375957610']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2020.09.20
[debug] Python version 2.7.18 (CPython) - Linux-5.4.0-52-lowlatency-x86_64-with-Ubuntu-20.04-focal
[debug] exe versions: ffmpeg 4.2.4, ffprobe 4.2.4
[debug] Proxy map: {}
[vimeo] 375957610: Downloading webpage
[vimeo] 375957610: Extracting information
[vimeo] 375957610: Downloading JSON metadata
[vimeo] 375957610: Downloading JSON metadata
[vimeo] 375957610: Checking Original video URL
[vimeo] 375957610: Downloading akfire_interconnect_quic m3u8 information
[vimeo] 375957610: Downloading akfire_interconnect_quic m3u8 information
[vimeo] 375957610: Downloading fastly_skyfire m3u8 information
[vimeo] 375957610: Downloading fastly_skyfire m3u8 information
[vimeo] 375957610: Downloading akfire_interconnect_quic MPD information
[vimeo] 375957610: Downloading akfire_interconnect_quic MPD information
[vimeo] 375957610: Downloading fastly_skyfire MPD information
[vimeo] 375957610: Downloading fastly_skyfire MPD information
[debug] Default format spec: bestvideo+bestaudio/best
[debug] Invoking downloader on u'https://skyfire.vimeocdn.com/1603213327-0xd98dc81dc5e3b83aece86172041ffd9e6f591f9d/89d05963-15ae-4baa-bff5-14becc915426/sep/video/e4e3bf25/playlist.m3u8'
[hlsnative] Downloading m3u8 manifest
[hlsnative] Total fragments: 80
[download] Destination: My Expanded View-375957610.fhls-fastly_skyfire_sep-5233.mp4
[download]   1.5% of ~74.04MiB at 597.91KiB/s ETA 02:41^C

Description

--rate-limit option is supported and works the same way as --limit-rate and -r, but it's not documented.

Including log files just to show that they both work.

[dstftw]

Aliases are not supposed to be documented.