fix word

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/10/static/app-pg-ctl.html
Description:

ref/pg_ctl-ref.sgml
337,338c337,339
<         The <replaceable>options</> should usually be surrounded by single
or
<         double quotes to ensure that they are passed through as a group.
---
>         The <replaceable>initdb-options</> should usually be surrounded
>         by single or double quotes to ensure that they are passed
through
>         as a group.