doc: fix typo in buffer.md

"alterered" ->  "altered"

PR-URL: #38243
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

doc/api/buffer.md

@@ -350,7 +350,7 @@ added: v15.7.0
 * `type` {string} The content-type for the new `Blob`
 
 Creates and returns a new `Blob` containing a subset of this `Blob` objects
-data. The original `Blob` is not alterered.
+data. The original `Blob` is not altered.
 
 ### `blob.text()`
 <!-- YAML