README: add a note that wire is no longer maintained

[findleyr]

Wire was archived by an automatic process because it was not being maintained. Unfortunately, it's true that there is no one maintaining wire, and we should make this clear in the README before re-archiving.

[shogo82148]

Could you release a new version of wire before re-archiving?
go install still fails.

% go install github.com/google/wire/cmd/wire@latest
# golang.org/x/tools/internal/tokeninternal
../../../../pkg/mod/golang.org/x/tools@v0.17.0/internal/tokeninternal/tokeninternal.go:78:9: invalid array length -delta * delta (constant -256 of type int64)

[findleyr]

@shogo82148 yes, I just wanted to get this commit in first. I just tagged v0.7.0, so wire@latest should no longer be broken.

[shogo82148]

@findleyr thanks, go install now works well.