Consider adjusting wording for `configured 'available'`

[korydraughn]

See the sentence which uses the phrase configured 'available' and consider rephrasing it so that it's clearer. https://github.com/irods/irods_docs/blob/d82772376e163f311c5d43c6cdc8eb70779fe177/docs/plugins/pluggable_authentication.md?plain=1#L5