Fix dynamic parameter regex replacement in processComplexMatch

The replace failed to inject the route parameter as the layer regex was
changed from `/^\/(?:([^\/]+?))\/?(?=\/|$)/i` to `/^(?:\/([^/]+?))\/?(?=\/|$)/i`.

Now both regex cases are taken into consideration. The regex was changed
to use optional non-capturing groups for the differences between the two
possible regex patterns.

Link to playground using the new regex format: https://regex101.com/r/cursDu/1

lib/generate-doc.js

@@ -102,7 +102,7 @@ function processComplexMatch (thing, keys) {
     // (i.e. /:id, /:name, etc...) with the name(s) of those parameter(s)
     // This could have been accomplished with replaceAll for Node version 15 and above
     // no-useless-escape is disabled since we need three backslashes
-    .replace(/\(\?\:\(\[\^\\\/\]\+\?\)\)/g, () => `{${keys[i++].name}}`) // eslint-disable-line no-useless-escape
+    .replace(/(?:\\\/)?\(\?\:(?:\\\/)?\(\[\^(?:\\)?\/\]\+\?\)\)\\\//, () => `/{${keys[i++].name}}/`) // eslint-disable-line no-useless-escape
     .replace(/\\(.)/g, '$1')
     // The replace below removes the regex used at the start of the string and
     // the regex used to match the query parameters