Better Links Across Ecosystem

[helloar14]

Some time ago, I saw a new issue regarding links not complete/not clear which makes potential users lost in the way when trying to find out about Inochi2D. After checking out a lot of parts, here is my findings.

Link	Inochi2D.com	itch.io (Creator)	itch.io (Session)	Creator Welcome	Creator About	Session About	Discord Server Guide
Official Website		Y	N	Y	N	N	N
itch.io	Y[1]			N	N	N	N
GitHub	Y[1]	Y	N	Y[3]	Y	N	N
Twitter	N	Y	Y	N	Y	N	N
YouTube	N	N	N	N	N	N	N
Discord	N[2]	Y	Y	Y	N	N

[1] There are 'Download' link and 'Other Versions' link. But I think it's better to have equally positioned buttons for itch.io and GitHub, labeled 'itch.io' and 'GitHub', with logo, since the itch.io button ('Download') is not a direct download and a link to the store page anyway.

[2] The Discord button links to online docs instead of Discord invite.

[3] There's a link to GitHub Sponsors, but I think separate link between Inochi2D project and Github Sponsors is better.

I believe every link should be easily found in those places. With appropriate logo if possible.