Updated doc for addition of background thread

Updated doc for addition of background thread and removed duplicate doc
entry.

Author: Joe Grasse

README.md

@@ -251,10 +251,12 @@ mysql> select * from latest_file_io limit 5;
 
 Summarizes memory use by user using the 5.7 Performance Schema instrumentation.
 
+When the user found is NULL, it is assumed to be a "background" thread.
+
 ##### Example
 
 ```SQL
-mysql> select * from memory_by_user_by_current_bytes WHERE user IS NOT NULL;
+mysql> select * from memory_by_user_by_current_bytes;
 +------+--------------------+-------------------+-------------------+-------------------+-----------------+
 | user | current_count_used | current_allocated | current_avg_alloc | current_max_alloc | total_allocated |
 +------+--------------------+-------------------+-------------------+-------------------+-----------------+
@@ -742,6 +744,8 @@ avg_tmp_tables_per_query: 189
 
 Summarizes statement activity, file IO and connections by user.
 
+When the user found is NULL, it is assumed to be a "background" thread.
+
 ##### Example
 
 ```SQL
@@ -823,6 +827,8 @@ mysql> select * from user_summary_by_file_io_type;
 
 Summarizes stages by user, ordered by user and total latency per stage.
 
+When the user found is NULL, it is assumed to be a "background" thread.
+
 ##### Example
 
 ```SQL
@@ -855,6 +861,8 @@ mysql> select * from user_summary_by_stages;
 
 Summarizes overall statement statistics by user.
 
+When the user found is NULL, it is assumed to be a "background" thread.
+
 ##### Example
 
 ```SQL
@@ -872,6 +880,8 @@ mysql> select * from user_summary_by_statement_latency;
 
 Summarizes the types of statements executed by each user.
 
+When the user found is NULL, it is assumed to be a "background" thread.
+
 ##### Example
 
 ```SQL

views/p_s/memory_by_user.sql

@@ -20,7 +20,7 @@
  * 
  * When the user found is NULL, it is assumed to be a "background" thread.  
  *
- * mysql> select * from memory_by_user_by_current_bytes WHERE user IS NOT NULL;
+ * mysql> select * from memory_by_user_by_current_bytes;
  * +------+--------------------+-------------------+-------------------+-------------------+-----------------+
  * | user | current_count_used | current_allocated | current_avg_alloc | current_max_alloc | total_allocated |
  * +------+--------------------+-------------------+-------------------+-------------------+-----------------+
@@ -59,7 +59,7 @@ SELECT IF(user IS NULL, 'background', user) AS user,
  * 
  * When the user found is NULL, it is assumed to be a "background" thread.  
  *
- * mysql> select * from x$memory_by_user_by_current_bytes WHERE user IS NOT NULL;
+ * mysql> select * from x$memory_by_user_by_current_bytes;
  * +------+--------------------+-------------------+-------------------+-------------------+-----------------+
  * | user | current_count_used | current_allocated | current_avg_alloc | current_max_alloc | total_allocated |
  * +------+--------------------+-------------------+-------------------+-------------------+-----------------+