Merge 4.9 into 5.0

[mongodb-php-bot]

Merge new changes from 4.9 into 5.0.

Commits

• DOCSP-51402: schema-flexible terminology (DOCSP-51402: schema-flexible terminology #3421): e0ff694
• DOCSP-49784: View file typo (DOCSP-49784: View file typo #3376): 0dc4a99
• DOCSP-49294 Add MDB Extension section to compat page (DOCSP-49294 Add MongoDB Extension 2.0 compat section #3357): 731f858
• PHPORM-319 Make branch 4.x compatible with driver v2 (PHPORM-319 Make branch 4.x compatible with driver v2 #3347): 486ec44

Resolving conflicts

To resolve any conflicts, check out the temporary branch and run the following command:

git merge 5.0

Ignoring changes

To ignore from the remote branch, first reset the temporary branch to 5.0 and manually merge using the `ours` merge strategy:

git reset --hard 5.0
git merge --strategy=ours 4.9

Then, push the temporary branch to upate the pull request.