Fix invalid DidChangeWatchedFilesRegistrationOptions

[juergenhoetzel]

Use naming according to the specification:

https://microsoft.github.io/language-server-protocol/specification#didchangewatchedfiles-notification-arrow_right

I'm using eglot. Emacs raises an error without this commit:

Debugger entered--Lisp error: (error "Keyword argument :list not one of (:watchers)")

Because of an invalid JSON message received from the server (JSON represented in Emacs data structures here):

(:jsonrpc "2.0" :id "1" :method "client/registerCapability" :params
      (:registrations
       [(:id "4e5af6ff-5a62-4ca7-bcd7-fb0582cd1c51" :method "workspace/didChangeWatchedFiles" :registerOptions
         (:list
          [(:patter "**/*")]))]))