Adding a body flux example

[germa89]

As the title.

@clatapie please can you have a look at this example?

@PipKat please could you review the grammar?

@mikerife I had to change some text and reorg a bit. Could you check everything still makes sense?

Thank you all!

Close #1998

[codecov]

Codecov Report

Merging #2233 (63d7e0b) into main (2221a7b) will decrease coverage by 4.56%.
Report is 78 commits behind head on main.
The diff coverage is 89.06%.

@@            Coverage Diff             @@
##             main    #2233      +/-   ##
==========================================
- Coverage   86.43%   81.87%   -4.56%     
==========================================
  Files          45       45              
  Lines        7971     8300     +329     
==========================================
- Hits         6890     6796      -94     
- Misses       1081     1504     +423     

[clatapie]

LGTM!

[PipKat]

@germa89 Provided text edits for consideration.