Fixing documentation for call collect

The documentation mentioned "collect call", however the server
is sending "collect_calls". Fixed the documentation so it matches
reality.

PS This was correct in the older documentation, somehow it got
changed.
Redmine#3285: document bundlesmatching() function
Merge pull request #209 from tzz/feature/3285-bundlesmatching

Redmine#3285: document bundlesmatching() function
Merge pull request #196 from cduclos/call_collect

Fixing documentation for call collect
Adding notes to readfile(), subsequently to internal code update