website: RU: Update to the latet EN revisions.
ru/search/_index.adoc (b6630fbab8b2befa8dd320535f2290e8b1082ce6)
ru/search/opensearch/_index.adoc (e84ab1b5742989c042ada16ffdd3aed11439eae4)
ru/releases/15.0R/errata.adoc (7b936eee18f57cb2b1f05d5120b9dc45275a163b)
The wording improved in several places.
Approved by: maxim (mentor)
Differential Revision: https://reviews.freebsd.org/D54533