remove trailing whitespace

doc/Language/performance.pod6

@@ -57,13 +57,13 @@ This will write the profile data as a series of SQL statements, suitable for ope
 
     # create a profile
     perl6 --profile --profile-filename=demo.sql -e 'say (^20).combinations(3).elems'
-    
+
     # create a SQLite database
     sqlite3 demo.sql
-    
+
     # load the profile data
     sqlite> .read demo.sql
-    
+
     # the query below is equivalent to the default view of the "Routines" tab in the HTML file
     sqlite> select
        ...>   case when r.name = "" then "<anon>" else r.name end,