* add md files for translation.
* start to translation fast-sync, code_structure. add file build_KR.md, states_KR.md
* add dandelion_KR.md && simulation_KR.md for Korean translation.
* add md files for translation.
* start to translation fast-sync, code_structure. add file build_KR.md, states_KR.md
* add dandelion_KR.md && simulation_KR.md for Korean translation.
* remove some useless md files for translation. this is rearrange set up translation order.
* add dot end of sentence & translate build.md in korean
* remove fast-sync_KR.md
* finish build_KR.md translation
* finish build_KR.md translation
* finish translation state_KR.md & add phrase in state.md to move other language md file
* translate blocks_and_headers.md && chain_sync.md in Korean
* add . in chain_sync.md , translation finished in doc/chain dir.
* fix some miss typos
* intial docs and images to describe receiving a block and simple sync.
* add some more description text
* svg -> png
* updated simple_sync diagram to include sync_head
* rename "block head" -> "body head"
* wip - sync_on_form diagram (kill me now)
* tidy up diagram for "sync on fork"
* consolidate the chain docs
