website/docs: add credentials prompt for rac doc (#14840) * Adds document * Typo * Clarified RAC endpoint sentence based on Tana's suggestion. * Update website/docs/add-secure-apps/providers/rac/rac_credentials_prompt.md * Small wording improvements * Added connection security type information * A word * Added to sidebar * Update website/docs/add-secure-apps/providers/rac/rac_credentials_prompt.md * Applied suggestions from Tana * Update website/docs/add-secure-apps/providers/rac/rac_credentials_prompt.md --------- Signed-off-by: Dewi Roberts <dewi@goauthentik.io> Co-authored-by: Dewi Roberts <dewi@goauthentik.io> Co-authored-by: Tana M Berry <tanamarieberry@yahoo.com> Co-authored-by: Jens L. <jens@goauthentik.io>