web: convert changelogs from old format

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

web/changelogs/4.6.md

@@ -0,0 +1,25 @@
+---
+title: "mute videos and proper soundcloud support"
+banner:
+    file: "shutup.webp"
+    alt: "a cat yawning, with a crossed out loudspeaker icon next to it"
+---
+i've been longing to implement both of these things, and here they finally are.
+
+service-related improvements:
+- you now can download videos with no audio! simply enable the "mute audio" option in settings > audio.
+- soundcloud module has been updated, and downloads should no longer break after some time.
+visual improvements:
+- moved some things around in settings popup, and added separators where separation is needed.
+- updated some texts in english and russian.
+- version and commit hash have been joined together, now they're a single unit.
+internal improvements:
+- updated api documentation to include isAudioMuted.
+- simplified the startup message.
+- created render elements for separator and explanation due to high duplication of them in the page.
+- fully deprecated GET method for API requests.
+- fixed some code quirks.
+here's how soundcloud downloads got fixed:
+
+previously, client_id was (stupidly) hardcoded. that means cobalt wasn't able to fetch song data if soundcloud web app got updated.
+now, cobalt tries to find the up-to-date client_id, caches it in memory, and checks if web app version has changed to update the id accordingly. you can see this change for yourself on github.