Support explicit renderer order #2803
Description
Problem
Similar to how preprocessors allow specifying the order (added in #1607), it might be a good idea to also support this for renderers. Apparently, from #2801, it was noted that some renderers depend on a particular order. Depending on the alphabetical order isn't probably the best way to make that dependency.
Proposed Solution
Support the same before/after keys from preprocessors in the output table.
Notes
mdbook v0.4.52