(example) lsp configuration without lsp-zero

[VonHeikemen]

The current version of lsp-zero does not work with the code in the tutorial 0 to LSP. So if anyone out there wants to configure the LSP servers without lsp-zero, this PR shows how.

If someone wants to upgrade the config to the current version of lsp-zero: here is the code adapted to the new version

[ravihlb]

Awesome, thank you for this! Just a heads up, though: packer's README recommends using either lazy.nvim or pckr.nvim since the packer repo is currently unmaintained