[template] Make Invited Expert status more inviting.

[jyasskin]

Say that Chairs should look out for potential Invited Experts, and point to how aspiring Invited Experts can apply.

This is in response to https://hachyderm.io/@thisismissem/113158694744132049 worrying that relying on the Invited Expert program will disenfranchise useful contributors and is meant as input to https://github.com/w3c/cg-council/issues/18. It's possible that this paragraph should also encourage non-Members to join as Members, but I want to make sure that's worded in a way that it doesn't discourage any self-employed people from asking to be IEs.

[ThisIsMissEm]

I wouldn't necessarily have something against becoming a W3C member, however, the current fee structure does not make this possible as a self-employed software engineer, where it is currently geared towards only allowing corporate participation, when so much of the Fediverse is built by self-employed people or small startups working towards a better web.