[DOC-11974] Added 4 new scriptlet pages and updated Eventing Examples page (Jon's feedback in #157)

[julia-cb]

@jon-strabala Hi Jon, I opened this new PR to cover the new files you created and other changes you made in #157 (figured this was easier than updating your PR directly and messing around with some extra files you accidentally pulled in).

I'll likely merge this over the weekend so that it makes it in for the release Monday morning, but I'm happy to go back in and make any necessary changes later.

Main changes in this PR:

• Added new pages for these functions:
  • advancedTouchOp
  • advancedSelfRecursion
  • advancedMutateInField
  • advancedMutateInArray
• Updated "Examples: Using the Eventing Service" with new pages
• Updated main nav.adoc file in docs-server with links to new pages (PR here)

Other changes:

• I went in and updated the wording in all pages under "Advanced Accessor Functions"
• The information on those pages hasn't changed - they were just updated to be consistent in style with the new pages added in this PR
• I also made some wording changes to the "Examples: Using the Eventing Service" page (no content changes besides style/language improvements)

[jon-strabala]

@julia-cb looks good to me