doc: fix typo in zlib.md · nodejs/node@b0fadbe

Original file line number	Diff line number	Diff line change
`@@ -419,7 +419,7 @@ Returns a new [DeflateRaw][] object with an [options][].`
`419`	`419`	`is set to 8 for raw deflate streams. zlib does not have a working implementation`
`420`	`420`	`of an 8-bit Window for raw deflate streams and would automatically set windowBit`
`421`	`421`	`to 9 if initially set to 8. Newer versions of zlib will throw an exception.`
`422`		`-This creates a potential DOS vector, and as such the behavior ahs been reverted`
	`422`	`+This creates a potential DOS vector, and as such the behavior has been reverted`
`423`	`423`	`in Node.js 8, 6, and 4. Node.js version 9 and higher will throw when windowBits`
`424`	`424`	`is set to 8.`
`425`	`425`