Fix the configuration index name

[ekarakashi]

Looks like the example code in bootstrapSession() expects to read a key sessionand not session_manager from the configuration.

Provide a narrative description of what you are trying to accomplish:

• Documentation enhacement

[michalbundyra]

We have ticket #71 to fix the whole documentation for Session Manager (I think we should at least mention default factory we have in the package).

Also I'd like to point #61 where we made a change.

/cc @froschdesign

[froschdesign]

@webimpress

I think we should at least mention default factory we have in the package

We must document the factory because this is the way the user should go. These manual configuration must be removed from all packages.

[weierophinney]

This repository has been closed and moved to laminas/laminas-session; a new issue has been opened at laminas/laminas-session#2.

[weierophinney]

This repository has been moved to laminas/laminas-session. If you feel that this patch is still relevant, please re-open against that repository, and reference this issue. To re-open, we suggest the following workflow:

• Squash all commits in your branch (git rebase -i origin/{branch})
• Make a note of all changed files (`git diff --name-only origin/{branch}...HEAD
• Run the laminas/laminas-migration tool on the code.
• Clone laminas/laminas-session to another directory.
• Copy the files from the second bullet point to the clone of laminas/laminas-session.
• In your clone of laminas/laminas-session, commit the files, push to your fork, and open the new PR.
  We will be providing tooling via laminas/laminas-migration soon to help automate the process.