Change Matrix/Element link to be more user friendly

[X] This is a feature request and not a bug report. Otherwise, please create a new bug report instead.
[X] Please check to see if this request (or a similar one) already exists.
[X] It's a single feature. Please don't request multiple features in one issue.

when a user drafts a private message, they're warned about lemmy pms not being secure and are advised to use element.io instead.

over time, this has become more and more unfriendly to individual/personal users.

it looks like this link was originally added back in the very first PR in this repo back in September 2020: https://github.com/LemmyNet/lemmy-ui/pull/1/commits/2eee93602687180976ad68de3d5f7a2cc4307cb3

back then, the page seems to have been fairly user friendly for individual users: https://web.archive.org/web/20200918192014/https://element.io/get-started

over time, this page slowly changed to include enterprise offers, prominently refer their sales team, over to being primarily marketed to enterprise users with a smaller note about free personal use below, removing the mention of free personal use and now outright scaring away users by prominently asking them to provide a bunch of personal details, including work email and company information, with only an inconspicuous "Want to download the free app?" link below that scary form.

https://matrix.org/try-matrix/ might be a reasonable alternative for this.

this is slightly related to #1893, but it can be addressed without supporting customization requested in #1893.

LemmyNet / lemmy-ui