Clarify documentation and examples for relations

[ten3roberts]

No description provided.

[codecov-commenter]

Codecov Report

Attention: 40 lines in your changes are missing coverage. Please review.

Comparison is base (2fd4fd7) 75.32% compared to head (53184f2) 75.63%.
Report is 11 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main      #10      +/-   ##
==========================================
+ Coverage   75.32%   75.63%   +0.31%     
==========================================
  Files          69       69              
  Lines        5231     5335     +104     
==========================================
+ Hits         3940     4035      +95     
- Misses       1291     1300       +9     

Files	Coverage Δ
src/archetypes.rs	97.46% <100.00%> (+0.06%)	⬆️
src/cascade/mod.rs	0.00% <ø> (ø)
src/entity/mod.rs	85.13% <ø> (ø)
src/fetch/mod.rs	78.57% <ø> (ø)
src/fetch/source.rs	61.90% <100.00%> (+2.38%)	⬆️
src/macros.rs	100.00% <ø> (ø)
src/query/dfs.rs	72.09% <100.00%> (+0.77%)	⬆️
src/query/topo.rs	77.10% <100.00%> (ø)
src/query/walk.rs	69.23% <100.00%> (ø)
src/world.rs	88.91% <100.00%> (+0.27%)	⬆️
... and 6 more

... and 18 files with indirect coverage changes

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[pherrymason]

Maybe here would be a good place to reinforce the target-subject terms after parent-child? Not sure.
Example:

This allows forming hierarchies such as *parent-child* (target-subject) relations for transforms and UI...

Not really sure because the relation can have any arbitrary direction, maybe this only applies to the child_of type of relation.

[ten3roberts]

Thank you, I've clarified it a bit more :)

[pherrymason]

I like it, everything seems more detailed.
Only comment is the one about reinforcing the target-subject, but I'm not totally sure it will be useful, up to you.