docs: add augmentation types import section to README and update type definitions

Added a new README section detailing how to import and use augmentation interfaces without pulling the entire library. Updated `package.json` exports to enable direct imports for augmentation types. Included example demonstrating custom augmentation implementation and usage.

package.json

@@ -15,6 +15,10 @@
     "./types/graphTypes": {
       "import": "./dist/types/graphTypes.js",
       "types": "./dist/types/graphTypes.d.ts"
+    },
+    "./types/augmentations": {
+      "import": "./dist/types/augmentations.js",
+      "types": "./dist/types/augmentations.d.ts"
     }
   },
   "engines": {