chore: move legacy sites off Azure

[mcdurdin]

Move legacy sites
https://blog.tavultesoft.com/
https://keymankeyboards.com/
https://r.keymanweb.com/
https://tavultesoft.com/
Note: legacy Keyman Sites Migration Google Doc

From #403

[ermshiperete]

See also keymanapp/r.keymanweb.com#10, keymanapp/keymankeyboards.com#4