Offer membership for ecosystem and associate members with a dedicated page

[Gnuxie]

@BramvdnHeuvel was asking in #ecosystem.forum:matrix.org whether we could provide a link to the website for people to sign up to ecosystem membership. However, we couldn't find a page suitable as the sign up form is linked only from the main membership page. The existing membership page is heavily centered towards paying members and we reason would be confusing/intimidating to community members. Since they would have to know beforehand that ecosystem membership existed as it is only mentioned in the diagram at the bottom of the page. And because the page is trying to attract a different group of people.

For now, we have linked directly to the form.

Context: https://matrix.to/#/%23ecosystem.forum%3Amatrix.org/%24jfOt5_e4z3kBtFcjusIj47JdwEHIOw5wD0PhfUqyDSg?via=neko.dev&via=matrix.org&via=0x.badd.cafe

[MTRNord]

Related: #2198