Add feature documentation for erasure coding, added in LU-10911. This should include in-tree documentation that describes the overall EC component layout (Ronnie's Documentation/ec.txt to ensure it is uptodate), updates to the Lustre Operations manual (see Lustre Manual Changes), as well as any changes to lfs mirror sub-commands in Documentation/man1 and parameter files in Documentation/man4.

There is also information available in the Lustre Erasure Coding Read-Only HLD.