Update README and keymaps for netrw navigation

Add command variants for netrw and update keymaps to improve
navigation experience. Store initial working directory as
project root for better symlink handling.

lua/settings.lua

@@ -5,6 +5,10 @@ vim.g.loaded_ruby_provider = 0
 vim.g.loaded_perl_provider = 0
 vim.g.loaded_node_provider = 0
 
+-- Store initial working directory as project root
+-- Used by netrw navigation to return to project root after following symlinks
+vim.g.project_root = vim.fn.getcwd()
+
 -- Enable project-local configuration files
 vim.opt.exrc = true -- Load .nvim.lua from project root
 vim.opt.secure = true -- Prompt before loading untrusted files