[MINOR][DOC] Add missing space after comma

Adding missing spaces after commas.

Closes apache#24205 from attilapiros/minor-doc-changes.

Authored-by: “attilapiros” <[email protected]>
Signed-off-by: Sean Owen <[email protected]>

Author: attilapiros

docs/configuration.md

@@ -2296,7 +2296,7 @@ In some cases, you may want to avoid hard-coding certain configurations in a `Sp
 instance, Spark allows you to simply create an empty conf and set spark/spark hadoop properties.
 
 {% highlight scala %}
-val conf = new SparkConf().set("spark.hadoop.abc.def","xyz")
+val conf = new SparkConf().set("spark.hadoop.abc.def", "xyz")
 val sc = new SparkContext(conf)
 {% endhighlight %}
 

docs/graphx-programming-guide.md

@@ -317,7 +317,7 @@ class Graph[VD, ED] {
   // Iterative graph-parallel computation ==========================================================
   def pregel[A](initialMsg: A, maxIterations: Int, activeDirection: EdgeDirection)(
       vprog: (VertexId, VD, A) => VD,
-      sendMsg: EdgeTriplet[VD, ED] => Iterator[(VertexId,A)],
+      sendMsg: EdgeTriplet[VD, ED] => Iterator[(VertexId, A)],
       mergeMsg: (A, A) => A)
     : Graph[VD, ED]
   // Basic graph algorithms ========================================================================

docs/mllib-statistics.md

@@ -239,7 +239,7 @@ Refer to the [`Statistics` Python docs](api/python/pyspark.mllib.html#pyspark.ml
 ### Streaming Significance Testing
 `spark.mllib` provides online implementations of some tests to support use cases
 like A/B testing. These tests may be performed on a Spark Streaming
-`DStream[(Boolean,Double)]` where the first element of each tuple
+`DStream[(Boolean, Double)]` where the first element of each tuple
 indicates control group (`false`) or treatment group (`true`) and the
 second element is the value of an observation.