add usage setion

Author: lucifayr

README.md

@@ -1,6 +1,6 @@
 # archwiki-nvim
 
-Have any ArchWiki article available immediately.
+Have any ArchWiki article available instantly
 
 
 ## Dependencies
@@ -31,3 +31,15 @@ Plug 'Jackboxx/archwiki-nvim'
         dependencies = { 'nvim-telescope/telescope.nvim' }
     }
 ```
+
+## Usage
+```lua
+-- read page as plain text
+vim.keymap.set('n', '<leader>awp', '<cmd>lua require("archwiki.api").select_page_from_local()<cr>')
+-- read page as markdown
+vim.keymap.set('n', '<leader>awm', '<cmd>lua require("archwiki.api").select_page_from_local("-f markdown")<cr>')
+-- read page as html
+vim.keymap.set('n', '<leader>awh', '<cmd>lua require("archwiki.api").select_page_from_local("-f html")<cr>')
+-- update list of locally stored pages in a category
+vim.keymap.set('n', '<leader>awu', '<cmd>lua require("archwiki.api").update_category_from_local()<cr>')
+```