Update 2-10_set-item-at-index.asciidoc

Another minor correction regarding the bounds of the assoc index parameter.
Merge https://github.com/clojure-cookbook/clojure-cookbook
additional corrections to assoc index bounds
Add Clinton Begin to acknowledgements
Merge pull request #364 from cbegin/assoc-index-corrections-2

Assoc index corrections 2
Merge branch 'first-edition'
qc edits and url merge
Merge branch 'master' into atlas-master