[docs] misc tweaks to docs

docs/core/config-default-app.md

@@ -2,7 +2,7 @@
 
 ### Enable Database Persistence
 
-Enabling database persistence (setPersistence) via JS for the default is no longer supported. This breaking change was added in v3 to prevent several race condition issues.
+Enabling database persistence (setPersistence) via JS for the default app is no longer supported. This breaking change was added in v3 to prevent several race condition issues around.
 
 You can still however easily enable this natively for the default app instance:
 

docs/core/config-rnfirebase.md

@@ -1,5 +1,8 @@
 <!-- TODO -->
 ### Log Options
 
+TODO - PR's welcome
+
 ### Debug Options
 
+TODO - PR's welcome

docs/modules/firestore.md

@@ -4,9 +4,9 @@
 RNFirebase mimics the [Firestore Web SDK](https://firebase.google.com/docs/reference/js/firebase.firestore), whilst
 providing support for devices in low/no data connection state.
 
-All Firestore operations are accessed via `firestore()`.
+All Firestore operations are accessed via `firestore()`. For detailed documentation of the supported methods demonstrated below please use the official firestore web sdk guides.
 
-Please note that Persistence (offline support) is enabled by default with Firestore on iOS and Android.
+?> Please note that Persistence (offline support) is enabled by default with Firestore on iOS and Android.
 
 ## Add and Manage Data
 
@@ -14,6 +14,8 @@ Please note that Persistence (offline support) is enabled by default with Firest
 
 Read information about a collection example:
 ```javascript
+import firebase from 'react-native-firebase';
+
 firebase.firestore()
   .collection('posts')
   .get()
@@ -31,6 +33,8 @@ firebase.firestore()
 
 Add to a collection example (generated ID):
 ```javascript
+import firebase from 'react-native-firebase';
+
 firebase.firestore()
   .collection('posts')
   .add({
@@ -44,6 +48,8 @@ firebase.firestore()
 
 Add to a collection example (manual ID):
 ```javascript
+import firebase from 'react-native-firebase';
+
 firebase.firestore()
   .collection('posts')
   .doc('post1')
@@ -60,6 +66,8 @@ firebase.firestore()
 
 There are multiple ways to read a document.  The following are equivalent examples:
 ```javascript
+import firebase from 'react-native-firebase';
+
 firebase.firestore()
   .doc('posts/posts1')
   .get((documentSnapshot) => {
@@ -76,6 +84,8 @@ firebase.firestore()
 
 Create a document example:
 ```javascript
+import firebase from 'react-native-firebase';
+
 firebase.firestore()
   .doc('posts/posts1')
   .set({
@@ -89,6 +99,8 @@ firebase.firestore()
 
 Updating a document example:
 ```javascript
+import firebase from 'react-native-firebase';
+
 firebase.firestore()
   .doc('posts/posts1')
   .update({
@@ -101,6 +113,8 @@ firebase.firestore()
 
 Deleting a document example:
 ```javascript
+import firebase from 'react-native-firebase';
+
 firebase.firestore()
   .doc('posts/posts1')
   .delete()
@@ -114,6 +128,8 @@ firebase.firestore()
 Writes, updates and deletes to documents can be batched and committed atomically as follows:
 
 ```javascript
+import firebase from 'react-native-firebase';
+
 const ayRef = firebase.firestore().doc('places/AY');
 const lRef = firebase.firestore().doc('places/LON');
 const nycRef = firebase.firestore().doc('places/NYC');
@@ -145,6 +161,8 @@ Coming soon
 
 Listen to collection updates example:
 ```javascript
+import firebase from 'react-native-firebase';
+
 firebase.firestore()
   .collection('cities')
   .where('state', '==', 'CA')
@@ -161,6 +179,8 @@ The snapshot handler will receive a new query snapshot every time the query resu
 
 Listen to document updates example:
 ```javascript
+import firebase from 'react-native-firebase';
+
 firebase.firestore()
   .doc('posts/post1')
   .onSnapshot((documentSnapshot) => {