docs(apiInject): re-add modified documentation in provide()

Author: benjamin-larsen

packages/runtime-core/src/apiInject.ts

@@ -16,6 +16,10 @@ export function provide<T, K = InjectionKey<T> | string | number>(
       warn(`provide() can only be used inside setup().`)
     }
   } else {
+    // by default an instance it creates its own provides object
+    // using parent provides object as prototype.
+    // this way in `inject` we can simply look up injections from direct
+    // parent and let the prototype chain do the work.
     const provides = currentInstance.provides
     // TS doesn't allow symbol as index type
     provides[key as string] = value