Convert MongoDB documentation from a top element of set to book

[haszi]

Convert all underlying elements as needed:

• <books> to <part>s or <chapter>s
• <article>s to <section>s

Move the Predefined Constants page from the Installing/Configuring section to its own

Change the following xml:ids:

• book.mongodb to mongodb.mongodb
• set.mongodb to book.mongodb
• book.bson to mongodb.bson

Please note that these changes only work when the accompanying doc-base changes are merged too (php/doc-base#138).

Note:
Please note that because of the difference between root chunks and container chunks in PhD (ie. a <book> and a <part>), the four pages linked to from the main MongoDB page (MongoDB, BSON, Monitoring and Exceptions) are only going to list their underlying classes without listing each method of each class.
E.g. the MongoDB Extension Classes page will only list the 19 classes belonging to that group of classes instead of listing the 19 classes plus all their 144 methods. As before, the methods are still listed on the pages of their respective classes.

[haszi]

This PR is now ready for review. The build failure is due to this PR only working in tandem with the accompanying doc-base PR (php/doc-base#138) as the overall hierarchy of the manual is defined in doc-base.

[cmb69]

Thank you!

This appears to be a very reasonable change to me, and I think it's okay for translations to catch up with this soon (given that the required changes are kept within bounds).

So, in my opinion, this is good to go.

[Girgias]

This looks reasonable to me and not that hard to update.

[haszi]

Please advise whether we can move forward with this and the doc-base PR or if I need to make any changes to this PR.

If this gets merged, I can open a PR with the same changes in some/all of the translation repos.

[cmb69]

Fine for me!

Maybe @alcaeus and @jmikola want to have a look, though.

[alcaeus]

Current set of changes LGTM! The build doesn't quite like it though ;)

[cmb69]

I think this just needs php/doc-base#138 to work.

[jmikola]

No objections from my end. Thanks for taking this on @haszi.

Please note that because of the difference between root chunks and container chunks in PhD (ie. a <book> and a <part>), the four pages linked to from the main MongoDB page (MongoDB, BSON, Monitoring and Exceptions) are only going to list their underlying classes without listing each method of each class.

That will be a welcome improvement.