web: convert changelogs from old format

https://gist.github.com/dumbmoron/3fc6c0c747d791928aba939976fd9304

web/changelogs/5.1.md

@@ -0,0 +1,45 @@
+---
+title: "the evil has been defeated"
+banner:
+    file: "happymeowth.webp"
+    alt: "meowth jumping up into the sky very excitedly"
+---
+hey, ever wanted to download a youtube video without a hassle? cobalt is here to help. this update fixes all issues related to youtube downloads.
+not only that, but it also introduces features never before seen in a downloader, such as youtube dub downloads! read below to see what's up :)
+
+<span class="text-backdrop">tl;dr:</span>
+- audio in youtube videos FINALLY no longer gets cut off.
+- you now can pick any video resolution you want (from 360p to 8k) and any possible youtube video codec (h264/av1/vp9).
+- you now can download youtube videos with dubs in your native language. just check settings > audio.
+- youtube processing has been vastly sped up.
+
+ok, now onto the nerdy part of changelog. this update is pretty huge and includes improvements across the board.
+
+service improvements:
+- all youtube functionality has been reworked. cobalt now relies on innertube apis, not web scraping.
+- random audio cut off issue has been fixed, let me know if it ever occurs again. (closes #62, #66, #75, #88).
+- added support for youtube dubs. currently it's using your browser's default language when enabled, but i have plans on making a picker. i'll ask people on twitter and mastodon if this feature is needed, and add a picker in next updates.
+- instead of adding more quality presets, i added granular quality options. pick whatever you like, from 360p up to 4320p (for all services, not just youtube).
+- replaced a format picker with codec picker for youtube. you can pick h264, av1, or vp9. all of them should work as expected (closes #88).
+- youtube audio files are now properly matched to corresponding video files.
+- it's now always possible to download pristine h264 720p/360p videos from youtube. these videos will work ANYWHERE, so they're default for mobile.
+- youtube requests are no longer permanently cached, ram usage should drop even further.
+- youtube video and audio file names now include codec and dub language when applicable.
+- max video and audio duration limits have been bumped up to 3 hours.
+- general performance of entire youtube download process has been greatly improved.
+- vk module has been reworked to be more compact and not make use of outdated technique of quality picking. should also be way more reliable.
+
+internal improvements:
+- cleaned up services config, all constants have been moved directly to modules for quicker access.
+- matching module has been slightly cleaned up.
+
+interface improvements:
+- many descriptions and error messages have been slightly tuned to be less wordy.
+- unnecessary title duplications in settings have been merged into one.
+- added more clarity to quality and codec descriptions.
+
+if you use cobalt api, please note that you have to update your creation to support new features.
+
+this is the second batch of 5.x improvements, there's way more to come. thank you for being here, i really appreciate your support.
+
+if you want to thank me (the developer), there's a nice tab under this changelog that has "donations" text on it. anything helps me continue developing and hosting the friendliest media downloader :D