Remove SC as we haven't tested it yet
Remove typos, consistent use of "legacy Search"
Better wording around disk usage

We don't know if having both RS and YZ running will require double the
space.  It will depend on the schema.  Benchmarks done by Luke Bakken
have shown Solr to use significantly less disk than merge index, in
one case only 5% of merge index.
Clean up wording around network/CPU/memory

No additional networking is needed for indexing as it is all done
across localhost.  More CPU will be used, especially for full text
analysis.  Reword the memory section to reflect that memory will be
dedicated to a different process.  Note not to make the heap too
large.
Change messaging for merge index files

There is no reason to keep the merge index files around.  Any
concurrent writes will immediately invalidate them causing a downgrade
to return incorrect results.  Upgrading to Yokozuna should be
considered a one way street.  If you go back the only way to be
consistent is to reindex everything.
Rewording of the outline
Add note that AAE is required
Perform full rolling upgrade before proceeding
Use core util fun rather than direct RPC
Need to use attach-direct

To get the ring you must attach directly to the node.
Rewrite step 6

There was a complete lack of detail and the instructions made no
sense.  I detailed how to determine when a full round of exchange has
occurred across the cluster.
Add rolling restart after step 9

A rolling restart must be done to purge the legacy Search commit
hooks.
Add optional note to step 7

Let users know that new Search can be queried before switching over.
Read SC, typo fix
Merge pull request #1150 from basho/rz/search-upgrade

Improvements to the search upgrade docs