Merge pull request ceph#65662 from aainscow/ec_direct_reads_docs

docs: Split Reads design (EC Direct Reads and Replica splits)

Author: aainscow

doc/dev/osd_internals/erasure_coding.rst

@@ -86,3 +86,4 @@ Table of contents
    Jerasure plugin <erasure_coding/jerasure>
    High level design document <erasure_coding/ecbackend>
    Erasure coding enhancements design document <erasure_coding/enhancements>
+   Direct reads design document <erasure_coding/direct_reads>