To optimise performance of lsp mode in emacs 27 and above
I have introduced a new dotfile variable to define the size
of data read from external processes. The default I have
set to the recommended setting from lsp-mode.
In addition I have introduced a new layer variable for
auto-complete-layer to define the minimum prefix length.
I have also added instructions to auto-complete's readme
how to set these variables to the recommended settings
for lsp-mode.
Changes inspired from #13507
d314cc7eef