[README] [nix] Add changes + tweak on the README. · ejgallego/coq-lsp@efbdc5b

Canceling since a higher priority waiting request for 'Github CI @ ejgallego:readme_nix_nit' exists

The operation was canceled.

An error has been caught in some system package index files, so the system package index files have been re-synchronised, and the system package installation has been retried: the process '/usr/bin/sudo' failed with exit code 100