doc: add N-API version 6 to table

[mhdawson]

We missed adding version 6 to the compatibility
table when we defined version 6. Add it along with the
versions that we know will include version 6.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• documentation is changed or added
• commit message follows commit guidelines

[jasnell]

My one concern is the scalability of this table as new levels are added. Might be worth refactoring to avoid the table growing too wide?

[richardlau]

The usual process is to add REPLACEME placeholders that get replaced in the release commit (i.e. 14.0.0).

[mhdawson]

@richardlau will that do the right thing when it gets backported?

[richardlau]

I think that depends on whether the commit is picked from current or master.

[gabrielschulhof]

Since this is a matrix adding REPLACEME for all versions will not do what we want. Maybe we should add REPLACEME for the version corresponding to the branch against which the commit is being applied, and hardcoded version values for all the other branches.

This means that when we backport this commit we'll necessarily have to edit it.

[richardlau]

I'm happy to break from convention/the usual process if it makes sense and does the right thing. I make a point of pointing out when we do diverge from the norm though so that we do so consciously.

[mhdawson]

@jasnell will think about how to refactor, but I'd like to land as is, as version 6 is already out and would like to avoid confusion in the short term.

[mhdawson]

Landed in 2abec12