custom-set: metadata: add title (#2125)

ee7 · web-flow · commit 0ca50ab2503a · 2022-10-11T16:24:38.000+02:00
Commit 6e57ab4 intended to add the title key to every exercise that lacked one, but custom-set was omitted.
diff --git a/exercises/custom-set/metadata.toml b/exercises/custom-set/metadata.toml
@@ -1 +1,2 @@
+title = "Custom Set"
 blurb = "Create a custom set type."

Original file line number	Diff line number	Diff line change
`@@ -1 +1,2 @@`
	`1`	`+title = "Custom Set"`
`1`	`2`	`blurb = "Create a custom set type."`