docs: spelling correction for "targetting" (#852)

Co-authored-by: Benjamin E. Coe <bencoe@google.com>

synthtool/gcp/templates/node_library/README.md

@@ -93,7 +93,7 @@ Our client libraries follow the [Node.js release schedule](https://nodejs.org/en
 Libraries are compatible with all current _active_ and _maintenance_ versions of
 Node.js.
 
-Client libraries targetting some end-of-life versions of Node.js are available, and
+Client libraries targeting some end-of-life versions of Node.js are available, and
 can be installed via npm [dist-tags](https://docs.npmjs.com/cli/dist-tag).
 The dist-tags follow the naming convention `legacy-(version)`.