add some primitive docs

README.md

@@ -10,8 +10,12 @@
 useUser(auth: auth.Auth, options?: ReactFireOptions): User
 ```
 
+[Example use](/master/sample-simple/src/Auth.js#L44)
+
 ### Firestore
 
+#### useFirestoreDoc
+
 ```ts
 function useFirestoreDoc(
   ref: firestore.DocumentReference,
@@ -19,6 +23,10 @@ function useFirestoreDoc(
 ): firestore.DocumentSnapshot;
 ```
 
+[Example use](/master/sample-simple/src/Firestore.js#L16)
+
+#### useFirestoreCollection
+
 ```ts
 function useFirestoreCollection(
   ref: firestore.CollectionReference,
@@ -26,8 +34,12 @@ function useFirestoreCollection(
 ): firestore.QuerySnapshot;
 ```
 
+[Example use](/master/sample-simple/src/Firestore.js#L57)
+
 ### Realtime Database
 
+#### useDatabaseObject
+
 ```ts
 function useDatabaseObject(
   ref: database.Reference,
@@ -35,6 +47,10 @@ function useDatabaseObject(
 ): QueryChange;
 ```
 
+[Example use](/master/sample-simple/src/RealtimeDatabase.js#L16)
+
+#### useDatabaseList
+
 ```ts
 function useDatabaseList(
   ref: database.Reference | database.Query,
@@ -42,8 +58,12 @@ function useDatabaseList(
 ): QueryChange[];
 ```
 
+[Example use](/master/sample-simple/src/RealtimeDatabase.js#L57)
+
 ### Cloud Storage for Firebase
 
+#### useStorageTask
+
 ```ts
 function useStorageTask(
   task: storage.UploadTask,
@@ -52,6 +72,10 @@ function useStorageTask(
 ): storage.UploadTaskSnapshot;
 ```
 
+[Example use](/master/sample-simple/src/Storage.js#L23)
+
+#### useStorageDownloadURL
+
 ```ts
 function useStorageDownloadURL(
   ref: storage.Reference,
@@ -59,6 +83,8 @@ function useStorageDownloadURL(
 ): string;
 ```
 
+[Example use](/master/sample-simple/src/Storage.js#L11)
+
 ## For development
 
 1. `yarn install`