docs($addToSet): use a simple example update for Field is Not an Array

Gianfrancø Palumbo · kay-kim · commit 6a540694313f · 2019-05-16T13:43:54.000-04:00
https://docs.mongodb.com/manual/reference/operator/update/addToSet/#field-is-not-an-array
diff --git a/source/reference/operator/update/addToSet.txt b/source/reference/operator/update/addToSet.txt
@@ -83,7 +83,7 @@ The following operation appends the array ``[ "c", "d" ]`` to the
 
    db.test.update(
       { _id: 1 },
-      { $addToSet: {letters: [ "c", "d" ] } }
+      { $addToSet: { letters: "c" } }
    )
 
 The ``letters`` array now includes the ``[ "c", "d" ]`` array

Original file line number	Diff line number	Diff line change
@@ -83,7 +83,7 @@ The following operation appends the array ``[ "c", "d" ]`` to the
`83`	`83`
`84`	`84`	`db.test.update(`
`85`	`85`	`{ _id: 1 },`
`86`		`- { $addToSet: {letters: [ "c", "d" ] } }`
	`86`	`+ { $addToSet: { letters: "c" } }`
`87`	`87`	`)`
`88`	`88`
`89`	`89`	The ``letters`` array now includes the ``[ "c", "d" ]`` array