[docs] update docs to reflect updated code using 128MiB

[halsaphi]

Change Description

Update to docs - zero impact to code base.

Change Type

Select ONE

• [x ] Documentation

• Stability bug fix

• Other

• Other - special case

Consensus Changes

• Consensus Changes

API Changes

• API Changes

Documentation Additions

• [x ] Documentation Additions

[allenhan2]

"Philip Halsall" doesn't have permission to trigger builds in "EOSIO Sync from Genesis",
could any sponsor of granting the permission to fire a service ticket? thanks,

[lparisc]

Few changes:

• Wrap the config options in codeblocks ``` ... ``` to render properly. It currently renders like this:
  "--backing-store arg (=chainbase) The storage for state, chainbase or rocksdb --rocksdb-threads arg Number of rocksdb threads for flush and compaction. Defaults to the number of available cores. --rocksdb-files arg (=-1) Max number of rocksdb files to keep open. -1 = unlimited. --rocksdb-write-buffer-size-mb arg (=128) Size of a single rocksdb memtable (in MiB)"
• Complete "Next Steps" section or remove title for now.
• docs/01_nodeos/02_usage/index.md must be updated to include the new 60_how-to-guides section

[gssagoo]

Looks good.

[gssagoo]

The changes to removing MiB from the --persistent-storage-write-buffer-size-mb parameter looks good. Also the comment change reflecting that we no longer default to the number of cores for --persistent-storage-num-threads looks good. thanks

[halsaphi]

re "docs/01_nodeos/02_usage/index.md must be updated to include the new 60_how-to-guides section" this doesn't match cleos and keod sections though ... should this be discussed?

Added something for you to review.