clipboard: support "lemonade" tool

runtime/autoload/provider/clipboard.vim

@@ -47,6 +47,11 @@ elseif exists('$DISPLAY') && executable('xclip')
   let s:paste['+'] = 'xclip -o -selection clipboard'
   let s:copy['*'] = 'xclip -quiet -i -selection primary'
   let s:paste['*'] = 'xclip -o -selection primary'
+elseif executable('lemonade')
+  let s:copy['+'] = 'lemonade copy'
+  let s:paste['+'] = 'lemonade paste'
+  let s:copy['*'] = 'lemonade copy'
+  let s:paste['*'] = 'lemonade paste'
 else
   echom 'clipboard: No clipboard tool available. See :help nvim-clipboard'
   finish

runtime/doc/nvim_clipboard.txt

@@ -22,6 +22,8 @@ is found in your `$PATH`.
 - xclip
 - xsel (newer alternative to xclip)
 - pbcopy/pbpaste (only for Mac OS X)
+- lemonade (useful for SSH machine)
+  https://github.com/pocke/lemonade
 
 The presence of a suitable clipboard tool implicitly enables the '+' and '*'
 registers.