docs(site): Retitling Installation to Download & Installation (#2127)
docs(site): Retitling Installation to Download & Installation (#2127)

We link to this page when telling people to download Kopia (see the download button at https://kopia.io), so it will be less confusing if we rename the page to "Download & Installation". We don't need to change the URL, just the title.
kopia/kopia,kopia/kopia,kopia/kopia,kopia/kopia