fixup: address review comment

doc/api/buffer.md

@@ -1996,8 +1996,8 @@ added: v0.1.90
   **Default:** `0`.
 * `length` {integer} Maximum number of bytes to write (written bytes will not
   exceed `buf.length - offset`). **Default:** `buf.length - offset`.
-  If the buffer has sufficient space from the offset, the string is written upto
-  `length`. If the buffer is short in space, only `buf.length - offset`
+  If the buffer has sufficient space from the offset, the string is written
+  up to `length`. If the buffer is short in space, only `buf.length - offset`
   bytes are written.
 * `encoding` {string} The character encoding of `string`. **Default:** `'utf8'`.
 * Returns: {integer} Number of bytes written.