update doc

README.textile

@@ -49,6 +49,7 @@ h2. Limitation
 * "where" condition not support in the following interface of play.db.Model.Factory implementation: 
 
 bc.. public List<play.db.Model> fetch(int offset, int size, String orderBy, String order, List<String> searchFields, String keywords, String where);
+
 p.
 * The generic is not working well, sometimes you need type casting. If someone could help, that would be very appreciate.
 
@@ -219,7 +220,8 @@ h4. How to create Entity with user defined @Id field?
 bc..     @Override public Object getId() {return name;}
     @Override protected void setId_(Object id) {name = id.toString();}
     protected static Object processId_(Object id) {return id.toString();}
-p.
+
+p..
 * Make sure you always populated your @Id field before calling model.save(), don't let framework to generate Id for you b/c framework has no knowledge on how to do it
 * It's better to keep your @Id field type to be java.lang.String.
 
@@ -228,7 +230,8 @@ h4. I got "Can not use dot-notation past  ..." exception when I try to query ent
 p. Basically this error occurred when you try to query an entity using referenced entity property. E.g. Post p = Post.filter("author.email", "bob@gmail.com").first(). The solution is:
 
 bc..     User bob = User.filter("email", "bob@gmail.com").first();
-     Post p = Post.filter("author", bob).first();
+      Post p = Post.filter("author", bob).first();
+
 p. If the relationship is embedded rather than reference, you can safely use "dot" notation to do the query
 
 h4. How do I know if an entity object is an new object just constructed in the memory or represents a data (either by save or load from db) in a db?

documentation/manual/home.textile

@@ -50,6 +50,7 @@ h2. Limitation
 
 bc.. public List<play.db.Model> fetch(int offset, int size, String orderBy, String order, List<String> searchFields, String keywords, String where);
 
+p.
 * The generic is not working well, sometimes you need type casting. If someone could help, that would be very appreciate.
 
 * "Or" condition query is doable but the interface might changed in future, use it with caution.
@@ -216,9 +217,23 @@ h4. How to create Entity with user defined @Id field?
 
 * Add @com.google.code.morphia.annotations.Id annotation to the field you want to use as an ID field, e.g. : @Id name;
 * Override the following methods declared in play.modules.morphia.Model:
-bc.     @Override public Object getId() {return name;}
+bc..     @Override public Object getId() {return name;}
     @Override protected void setId_(Object id) {name = id.toString();}
     protected static Object processId_(Object id) {return id.toString();}
 
+p..
 * Make sure you always populated your @Id field before calling model.save(), don't let framework to generate Id for you b/c framework has no knowledge on how to do it
-* It's better to keep your @Id field type to be java.lang.String.
+* It's better to keep your @Id field type to be java.lang.String.
+
+h4. I got "Can not use dot-notation past  ..." exception when I try to query entity using relationship, what happened?
+
+p. Basically this error occurred when you try to query an entity using referenced entity property. E.g. Post p = Post.filter("author.email", "bob@gmail.com").first(). The solution is:
+
+bc..     User bob = User.filter("email", "bob@gmail.com").first();
+      Post p = Post.filter("author", bob).first();
+
+p. If the relationship is embedded rather than reference, you can safely use "dot" notation to do the query
+
+h4. How do I know if an entity object is an new object just constructed in the memory or represents a data (either by save or load from db) in a db?
+
+p. Use obj.isNew()