(docs) Update the sqls URL to match the current organization

[suzuki]

About

The sqls document said:

Installation
go install github.com/lighttiger2505/sqls@latest

But it failed like this:

$ go install github.com/lighttiger2505/sqls@latest
go: github.com/lighttiger2505/sqls@latest: version constraints conflict:
        github.com/lighttiger2505/sqls@v0.2.28: parsing go.mod:
        module declares its path as: github.com/sqls-server/sqls
                but was required as: github.com/lighttiger2505/sqls

sqls-server/sqls is successful:

$ go install github.com/sqls-server/sqls@latest

[jcs090218]

Thanks!