vim/c: added vim setup and c language setup

- added vim setup
- added vim autocomplete guide based on coc
- added c support by coc lsp
- added c setup

wiki/linux/vim/vim-plug.md

@@ -0,0 +1,35 @@
+# Vim-Plug
+
+[Vim-Plug](https://github.com/junegunn/vim-plug) is a minimalist plugin manager.
+
+## Installation
+
+You can add the following lines to your vim config file to make sure vim-plug is
+installed with the correct folder-structure.
+
+```vimscript
+if ! filereadable(expand('~/.config/nvim/autoload/plug.vim'))
+    echo "Downloading junegunn/vim-plug to manage plugins..."
+    silent !mkdir -p ~/.config/nvim/autoload/
+    silent !curl "https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim" > ~/.config/nvim/autoload/plug.vim
+    autocmd VimEnter * PlugInstall
+endif
+```
+
+Below is an example plugin section.
+
+```vimscript
+call plug#begin('~/.local/share/nvim/plugged')
+Plug 'airblade/vim-gitgutter'
+Plug 'tpope/vim-surround'
+Plug 'uiiaoo/java-syntax.vim' , {'for': 'java'}
+call plug#end()
+```
+
+## Important commands
+
+- `:PlugInstall` - install plugins specified in the Plug section
+- `:PlugClean` - remove plugins that are not specified in the Plug section
+
+For both of these command remember to write the file and reload the buffer if
+you just added a new plugin or removed one.