chore(docs): Update trailingSlash default wording (#34898)

Co-authored-by: gatsbybot <[email protected]>

Author: pragmaticpat

docs/docs/reference/config-files/gatsby-config.md

@@ -172,7 +172,7 @@ Configures the creation of URLs and whether to remove, append, or ignore trailin
 - `never`: Remove all trailing slashes on each URL, e.g. `/x/` to `/x`.
 - `ignore`: Don't automatically modify the URL
 
-Until Gatsby v4 it'll be set to `legacy` by default, in Gatsby v5 the default mode will be `always`. Gatsby Cloud automatically handles and supports the `trailingSlash` option, any other hosting provider (or if you're managing this on your own) should follow the "Redirects, and expected behavior from the hosting provider" section on the [initial RFC](https://github.com/gatsbyjs/gatsby/discussions/34205).
+The default setting for this option is `legacy` in order to preserve existing behavior for current users. In Gatsby v5 the default mode will be `always`. Gatsby Cloud automatically handles and supports the `trailingSlash` option. Alternate hosting providers (or if you're managing this on your own) should follow the "Redirects, and expected behavior from the hosting provider" section on the [initial RFC](https://github.com/gatsbyjs/gatsby/discussions/34205).
 
 ## polyfill