Update documentation references for keymaps and logs

- Changed references from KEYMAPS.md to README.md in multiple files.
- Updated decision log entries to reflect the new documentation structure.

lua/keymaps_reference.lua

@@ -1,6 +1,6 @@
 local M = {}
 
-local reference_filename = "KEYMAPS.md"
+local reference_filename = "README.md"
 local reference_path = vim.fn.stdpath("config") .. "/" .. reference_filename
 
 local function read_reference()
@@ -9,7 +9,7 @@ local function read_reference()
   if not fd then
     return {
       ("Keymap reference file not found: %s"):format(reference_path),
-      "Create KEYMAPS.md to document mappings.",
+      "Create README.md to document mappings.",
     }
   end
 
@@ -19,7 +19,7 @@ local function read_reference()
   fd:close()
 
   if #lines == 0 then
-    lines = { "KEYMAPS.md is empty." }
+    lines = { "README.md is empty." }
   end
 
   return lines
@@ -69,6 +69,6 @@ end
 
 vim.api.nvim_create_user_command("KeymapsGuide", function()
   M.open_reference()
-end, { desc = "Show KEYMAPS.md in a floating window" })
+end, { desc = "Show README.md keymap reference in a floating window" })
 
 return M