doc: fix typo in ngtcp2 readme

PR-URL: #43767
Fixes: #43766
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Qingyu Deng <i@ayase-lab.com>

Author: dancastillo

deps/ngtcp2/README.md

@@ -17,7 +17,7 @@ We only use a subset of the sources for each.
 
 The `nghttp3` library depends on `ngtcp2`. Both should always be updated
 together. From `ngtcp2` we only want the contents of the `lib` and `crypto`
-directories; from `nghttp3` we only want the contents o the `lib`.
+directories; from `nghttp3` we only want the contents of the `lib`.
 
 ### Updating ngtcp2