Add section about Enumerable#lazy

Author: ydakuka

README.adoc

@@ -4950,6 +4950,27 @@ LOREM
 "when an unknown printer took a galley of type and scrambled it to make a type specimen book."
 ----
 
+== Enumerable
+
+=== lazy [[lazy]]
+
+Use `Enumerable#lazy` in combination with methods like `.first` or `.take`, especially for operations on large collections or datasets, because it avoids the need to process the entire collection.
+
+[source,ruby]
+----
+size = 10
+
+# bad
+(0..10_000_000).uniq { |x| x + 2 }.first(size)
+(0..10_000_000).map { |x| x + 2 }.first(size)
+(0..10_000_000).select { |x| x + 2 }.take(size)
+
+# good
+(0..10_000_000).lazy.uniq { |x| x + 2 }.first(size)
+(0..10_000_000).lazy.map { |x| x + 2 }.first(size)
+(0..10_000_000).lazy.select { |x| x + 2 }.take(size)
+----
+
 == Heredocs
 
 === Squiggly Heredocs [[squiggly-heredocs]]