docs: add overview guides to specific modules

[matthewmayer]

fix #1928

examples:

[codecov]

Codecov Report

Merging #1929 (6777928) into next (88e561a) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 6777928 differs from pull request most recent head 9d902b6. Consider uploading reports for the commit 9d902b6 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #1929      +/-   ##
==========================================
+ Coverage   99.61%   99.63%   +0.01%     
==========================================
  Files        2460     2450      -10     
  Lines      239942   239952      +10     
  Branches     1274     1276       +2     
==========================================
+ Hits       239024   239068      +44     
+ Misses        895      862      -33     
+ Partials       23       22       -1     

Impacted Files	Coverage Δ
src/modules/airline/index.ts	100.00% <100.00%> (ø)
src/modules/animal/index.ts	100.00% <100.00%> (ø)
src/modules/color/index.ts	99.79% <100.00%> (+<0.01%)	⬆️
src/modules/commerce/index.ts	100.00% <100.00%> (ø)
src/modules/company/index.ts	100.00% <100.00%> (ø)
src/modules/database/index.ts	100.00% <100.00%> (ø)
src/modules/datatype/index.ts	100.00% <100.00%> (ø)
src/modules/date/index.ts	100.00% <100.00%> (ø)
src/modules/finance/index.ts	100.00% <100.00%> (ø)
src/modules/git/index.ts	100.00% <100.00%> (ø)
... and 14 more

... and 106 files with indirect coverage changes

[ST-DDT]

I think the links wont work locally in our IDEs.
Should we use fully qualified links instead (and convert them to absolute links in the docs build)?

[matthewmayer]

I think the links wont work locally in our IDEs.

Should we use fully qualified links instead (and convert them to absolute links in the docs build)?

What would a fully qualified link look like in markdown?

[ST-DDT]

What would a fully qualified link look like in markdown?

It starts with https. Sorry if I messed up the terms.

[matthewmayer]

Which hostname though?

[ST-DDT]

I thought about using next until we release v8 and adjust the main docs version. In the docs build we should adjust it to absolute links (without hostname) though.
But I'm open to suggestions.

[ST-DDT]

Please also add a test to our signature tests

[matthewmayer]

Please also add a test to our signature tests

the existing signature snapshot tests only seem to be for method signatures, not sure how to add for module comments?