Auditing: fix doc example of evm circuit

[DreamWuGit]

Description

table example mismatch code implementation. update as following:

1. In the table, change q_step_first to enabled for only first row of the first step
2. change q_step_last is enabled for only last row of the last step
3. adjust num_rows_until_next_step to zero at first row of each step. Thus the column should be 0, 5, 4, 3, 2, 1,
   0, 6, 5, ... instead of 5, 4, 3, 2, 1, 0, 6, 5, ....

Issue Link

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