nazca #116939 Update the doc [validation pending]

There are some mistakes in the doc (typos…) to correct.

It would be nice to add a paragraph about the online demo too.

prioritynormal
typeenhancement
done in0.2.0
load0.100
load left0.000
closed by#97900fe196c9 [doc] Typo + a litte text about the online demo. (closes #116939)
patch[doc] Typo + a litte text about the online demo. (closes #116939) [applied]