minor: fixing import
build: refactoring migration script
DOCS-1541: improving the backup service documentation cross references
DOCS-1507 clarification about windows and numa
DOCS-1456: compaction removes extra padding when usePowerOf2Sizes is set.
DOCS-1542: adding notes about mixed version clusters and hashed shard keys
Fixed verbage about non-voting members to resolve DOCS-1538

You cannot have more than 12 members.  You cannot have more than 7 voting members.  So fixing this sentence to explain non-voting members are needed in replica sets with more than 7 members (not 12).