helix: codebook-lsp got renamed

helix/languages.toml

···
 ## LSPs
 
 [language-server]
-codebook = { command = "codebook", args = ["serve"] }
+codebook = { command = "codebook-lsp", args = ["serve"] }
 fish-lsp = { command = "fish-lsp", args = [
   "start",
 ], environment = { "fish_lsp_show_client_popups" = "false" } }