Merge document corrections in LBM

[torao]

Description

This PR is a document amendment to Ostracon's latest design changes.

• The role of "voter" and the election of voters have been removed.
• Minor wording changes to the English text and its application to the Japanese version.

See fix/merge_docs_from_lbm branch for a markdown view of this deliverable.

Closes: #XXX

[ulbqb]

Regarding the Japanese version, I thought it would be better to unify the following.

• 合意メカニズム、合意アルゴリズム、コンセンサススキーム
• 未確定、未承認

[torao]

@ulbqb
未承認 and コンセンサススキーム unified as 未確定 and 合意メカニズム respectively. But Algorithms are left separate as it's unnatural to treat them as essentially equivalent to Mechanisms.