add simple footnote text function

[gravesti]

Helps to resolve #26
Relates to #35

[github-actions]

Code Coverage Summary

Filename                   Stmts    Miss  Cover    Missing
-----------------------  -------  ------  -------  ---------
R/bucher.R                    22       9  59.09%   37, 63-72
R/data_generation.R           20      20  0.00%    36-73
R/maic_unanchored_tte.R       85      85  0.00%    25-164
R/matching.R                 137     133  2.92%    31-311
R/process_data.R             101     101  0.00%    39-261
R/survival-helper.R          139     139  0.00%    12-245
TOTAL                        504     487  3.37%

Diff against main

Filename        Stmts    Miss  Cover
------------  -------  ------  -------
R/matching.R       +4       0  +2.92%
TOTAL              +4       0  +0.77%

Results for commit: 3add64a

Minimum allowed coverage is 80%

♻️ This comment has been updated with latest results

[miranta-antoniou-roche]

This looks great, thank you Isaac!