docs: add default list of enabled providers

README.md

@@ -63,6 +63,14 @@
     -- adjusts spacing to ensure icons are aligned
     nerd_font_variant = 'mono',
 
+    -- default list of enabled providers defined so that you can extend it
+    -- elsewhere in your config, without redefining it, via `opts_extend`
+    sources = {
+      completion = {
+        enabled_providers = { 'snippets', 'lsp', 'buffer', 'path' },
+      },
+    },
+
     -- experimental auto-brackets support
     -- accept = { auto_brackets = { enabled = true } }