Add GraphX upgrade guide from Spark 0.9.1

docs/graphx-programming-guide.md

@@ -86,6 +86,12 @@ support the [Bagel API](api/scala/index.html#org.apache.spark.bagel.package) and
 [Bagel programming guide](bagel-programming-guide.html). However, we encourage Bagel users to
 explore the new GraphX API and comment on issues that may complicate the transition from Bagel.
 
+## Upgrade Guide from Spark 0.9.1
+
+GraphX in Spark {{site.SPARK_VERSION}} contains one user-facing interface change from Spark 0.9.1. [`EdgeRDD`][EdgeRDD] may now store adjacent vertex attributes to construct the triplets, so it has gained a type parameter. The edges of a graph of type `Graph[VD, ED]` are of type `EdgeRDD[ED, VD]` rather than `EdgeRDD[ED]`.
+
+[EdgeRDD]: api/scala/index.html#org.apache.spark.graphx.EdgeRDD
+
 # Getting Started
 
 To get started you first need to import Spark and GraphX into your project, as follows:
@@ -145,12 +151,12 @@ the vertices and edges of the graph:
 {% highlight scala %}
 class Graph[VD, ED] {
   val vertices: VertexRDD[VD]
-  val edges: EdgeRDD[ED]
+  val edges: EdgeRDD[ED, VD]
 }
 {% endhighlight %}
 
-The classes `VertexRDD[VD]` and `EdgeRDD[ED]` extend and are optimized versions of `RDD[(VertexID,
-VD)]` and `RDD[Edge[ED]]` respectively.  Both `VertexRDD[VD]` and `EdgeRDD[ED]` provide  additional
+The classes `VertexRDD[VD]` and `EdgeRDD[ED, VD]` extend and are optimized versions of `RDD[(VertexID,
+VD)]` and `RDD[Edge[ED]]` respectively.  Both `VertexRDD[VD]` and `EdgeRDD[ED, VD]` provide  additional
 functionality built around graph computation and leverage internal optimizations.  We discuss the
 `VertexRDD` and `EdgeRDD` API in greater detail in the section on [vertex and edge
 RDDs](#vertex_and_edge_rdds) but for now they can be thought of as simply RDDs of the form:
@@ -302,7 +308,7 @@ class Graph[VD, ED] {
   val degrees: VertexRDD[Int]
   // Views of the graph as collections =============================================================
   val vertices: VertexRDD[VD]
-  val edges: EdgeRDD[ED]
+  val edges: EdgeRDD[ED, VD]
   val triplets: RDD[EdgeTriplet[VD, ED]]
   // Functions for caching graphs ==================================================================
   def persist(newLevel: StorageLevel = StorageLevel.MEMORY_ONLY): Graph[VD, ED]
@@ -908,7 +914,7 @@ val setC: VertexRDD[Double] = setA.innerJoin(setB)((id, a, b) => a + b)
 
 ## EdgeRDDs
 
-The `EdgeRDD[ED]`, which extends `RDD[Edge[ED]]` organizes the edges in blocks partitioned using one
+The `EdgeRDD[ED, VD]`, which extends `RDD[Edge[ED]]` organizes the edges in blocks partitioned using one
 of the various partitioning strategies defined in [`PartitionStrategy`][PartitionStrategy].  Within
 each partition, edge attributes and adjacency structure, are stored separately enabling maximum
 reuse when changing attribute values.
@@ -918,11 +924,11 @@ reuse when changing attribute values.
 The three additional functions exposed by the `EdgeRDD` are:
 {% highlight scala %}
 // Transform the edge attributes while preserving the structure
-def mapValues[ED2](f: Edge[ED] => ED2): EdgeRDD[ED2]
+def mapValues[ED2](f: Edge[ED] => ED2): EdgeRDD[ED2, VD]
 // Revere the edges reusing both attributes and structure
-def reverse: EdgeRDD[ED]
+def reverse: EdgeRDD[ED, VD]
 // Join two `EdgeRDD`s partitioned using the same partitioning strategy.
-def innerJoin[ED2, ED3](other: EdgeRDD[ED2])(f: (VertexId, VertexId, ED, ED2) => ED3): EdgeRDD[ED3]
+def innerJoin[ED2, ED3](other: EdgeRDD[ED2, VD])(f: (VertexId, VertexId, ED, ED2) => ED3): EdgeRDD[ED3, VD]
 {% endhighlight %}
 
 In most applications we have found that operations on the `EdgeRDD` are accomplished through the