Update benchmark.asciidoc

Fixed incorrect parameter spec for benchmark nodes
Use unlimited flush_threshold_ops for translog

Currently we use 5k operations as a flush threshold. Indexing 5k documents
per second is rather common which would cause the index to be committed on
the lucene level each time the flush logic runs which is 5 seconds by default.
We should rather use a size based threshold similar to the lucene index writer
that doesn't cause such agressive commits which can slow down indexing significantly
especially since they cause the underlying devices to fsync their data.
[TEST] Randomize translog setting per index
[DOCS] Add /_search_shards documentation
Improved bloom filter hashing
Make improvements to how bloom filter hashing works based on guava 17 upcoming changes, see more here (https://code.google.com/p/guava-libraries/issues/detail?id=1119)
In order to do it, introduce a hashing enum, and use the (unused until now) hash type serialization to choose the correct hashing used based on serialized version.
Also, move to use our own optimized murmur hash for the new hashing logic.
Parse has_child query/filter after child type has been parsed

Fixes #5783
Fixes #5838
[SPEC] Renamed benchmark endpoints

benchmark.submit -> benchmark
benchmark.list   -> list_benchmarks
benchmark.abort  -> abort_benchmark

And fixed the related tests
[SPEC] Added missing list_benchmarks test
[SPEC] The scroll_id is no longer a required qs param
Can be passed in the body instead
[DOCS] getting started tutorial
[SPEC] Added path without scroll_id to clear_scroll