chore: fix various typos

lua/plugins/null-ls.lua

@@ -1,6 +1,6 @@
 if true then return {} end -- REMOVE THIS LINE TO ACTIVATE THIS FILE
 
--- Exapmle customization of Null-LS sources
+-- Example customization of Null-LS sources
 return {
   "jose-elias-alvarez/null-ls.nvim",
   opts = function(_, config)

lua/plugins/treesitter.lua

@@ -1,6 +1,6 @@
 if true then return {} end -- REMOVE THIS LINE TO ACTIVATE THIS FILE
 
--- Exapmle customization of Treesitter
+-- Example customization of Treesitter
 return {
   "nvim-treesitter/nvim-treesitter",
   opts = function(_, opts)