add suggested sentence to survival vignette

[danielinteractive]

Thanks to Dong for the suggestion!

[github-actions]

Code Coverage Summary

Filename                     Stmts    Miss  Cover    Missing
-------------------------  -------  ------  -------  ------------
R/bias.R                        34       0  100.00%
R/find_data.R                    3       0  100.00%
R/predict_couterfactual.R       77       0  100.00%
R/prediction_cf.R               22       0  100.00%
R/robin_glm.R                   49       1  97.96%   40
R/robin_lm.R                    28       0  100.00%
R/surv_effect.R                 67       0  100.00%
R/survival_cov_adj.R           146       0  100.00%
R/survival_score.R             294       0  100.00%
R/survival.R                   345       1  99.71%   603
R/treatment_effect.R           101       1  99.01%   51
R/utils.R                      204       3  98.53%   83, 115, 119
R/variance_anhecova.R           44       0  100.00%
R/variance_hc.R                 10       0  100.00%
TOTAL                         1424       6  99.58%

Diff against main

Filename      Stmts    Miss  Cover
----------  -------  ------  --------
TOTAL             0       0  +100.00%

Results for commit: 9b41271

Minimum allowed coverage is 80%

♻️ This comment has been updated with latest results

[github-actions]

Unit Tests Summary

  1 files   13 suites   13s ⏱️
142 tests  96 ✅ 46 💤 0 ❌
348 runs  284 ✅ 64 💤 0 ❌

Results for commit 9b41271.