update doc

[clarkliming]

update doc to solve the issue in checks

[github-actions]

🧪 $Test coverage: 99.30%$

Code Coverage Summary

Filename               Stmts    Miss  Cover    Missing
-------------------  -------  ------  -------  ---------
R/assertions.R            54       0  100.00%
R/co_relevels.R           17       0  100.00%
R/cut_by_group.R          15       0  100.00%
R/dm_explicit_na.R        38       0  100.00%
R/filter.R                22       0  100.00%
R/join_adsub_adsl.R      115       0  100.00%
R/pivot.R                 73       0  100.00%
R/propagate.R             45       2  95.56%   74, 119
R/reformat.R              72       0  100.00%
R/rules.R                 31       0  100.00%
R/unite.R                 63       2  96.83%   96, 104
R/utils.R                 27       0  100.00%
TOTAL                    572       4  99.30%

Results for commit: 8ad0e01

Minimum allowed coverage is 80%

♻️ This comment has been updated with latest results

[github-actions]

Unit Tests Summary

    1 files    12 suites   5s ⏱️
  76 tests   73 ✔️ 3 💤 0 ❌
250 runs  244 ✔️ 6 💤 0 ❌

Results for commit 7f70590.

[duanx9]

all set