documentation for legacy branch

[shadowwa]

Il y follow the documentation and use

Plug 'mhinz/vim-signify', { 'branch': 'legacy' }

for vim without patch-8.0.902 I got this error when updating plugin:

x vim-signify:
    fatal: origin/legacy - not something we can merge

it seems that it is because there is no 'legacy' branch

since there is a 'legacy' tag, I replaced the line, in my vimrc, with

Plug 'mhinz/vim-signify', { 'tag': 'legacy' }