docs: add docs and ignores to the code files

[incendial]

What is the purpose of this pull request? (put an "X" next to an item)

[X] Documentation update
[ ] Bug fix
[ ] New rule
[ ] Changes an existing rule
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

[codecov]

Codecov Report

Merging #516 (c2d1e97) into master (7e30f04) will not change coverage.
The diff coverage is n/a.

❗ Current head c2d1e97 differs from pull request most recent head 7bfc95c. Consider uploading reports for the commit 7bfc95c to get more accurate results

@@           Coverage Diff           @@
##           master     #516   +/-   ##
=======================================
  Coverage   84.72%   84.72%           
=======================================
  Files         217      217           
  Lines        4438     4438           
=======================================
  Hits         3760     3760           
  Misses        678      678           

Impacted Files	Coverage Δ
lib/src/analyzer_plugin/analyzer_plugin.dart	0.00% <ø> (ø)
.../anti_patterns/anti_patterns_list/long_method.dart	100.00% <ø> (ø)
...tterns/anti_patterns_list/long_parameter_list.dart	100.00% <ø> (ø)
lib/src/analyzers/lint_analyzer/lint_analyzer.dart	92.74% <ø> (ø)
lib/src/analyzers/lint_analyzer/lint_config.dart	76.92% <ø> (ø)
...complexity/cyclomatic_complexity_flow_visitor.dart	100.00% <ø> (ø)
...t/halstead_volume/halstead_volume_ast_visitor.dart	100.00% <ø> (ø)
...t/maximum_nesting_level/nesting_level_visitor.dart	100.00% <ø> (ø)
...analyzers/lint_analyzer/metrics/scope_visitor.dart	100.00% <ø> (ø)
...analyzer/models/internal_resolved_unit_result.dart	100.00% <ø> (ø)
... and 77 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7e30f04...7bfc95c. Read the comment docs.