Fix documentation of `dot_product()`

Fix wrong comment and add better unitary test for dot_product

changed milestone to %REVIEW_CAN_START

added documentation label

requested review from @sli

changed milestone to %REVIEW_COMPLETED_AND_APPROVED

approved this merge request

@lthomas, thank you very much, I think there are very good changes. The previous comment did lead to some confusion on my side...

And the new test is much better, too, as it allows to compare the optimized implementation results with the results of a straight forward implementation!

OAI RAN-Container-Parent build (3617): passed (https://jenkins-oai.eurecom.fr/job/RAN-Container-Parent/3617/)

resolved all threads

changed milestone to %OK_TO_BE_MERGED

changed title from fix doc only to Fix doc{+umentation of dot_product()+}

mentioned in merge request !1877 (merged)

mentioned in commit 1a0c0cd1

mentioned in merge request !1885 (merged)

mentioned in merge request !1906 (merged)

mentioned in commit 214aa505

merged