The CI takes a long time (sometimes hours) and shouldn't hold up
documentation-only commits. We may also find CI for other changes starts
faster, if we're not using up as many credits. When we process documentation
into something nicer (like `nimbus.guide`) we'll need to revisit this.
Syntax from [example ignoring paths](https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#example-ignoring-paths).
Signed-off-by: Jamie Lokier <jamie@shareable.org>
why:
vm2 enabled by ENABLE_VM2=1 behaves as vm without ENABLE_EVMC=1 until
it doesn't in some future fatch set. this leaves some wiggle room
to work on a vm copy without degrading the original implementation.
details:
+ additional make flag ENABLE_VM2=1 (or ENABLE_VM2=0 to explicitely disable)
+ when both flags ENABLE_EVMC=1 and ENABLE_VM2=1 are present, the former
flag ENABLE_EVMC=1 takes precedence, this is implemented at the NIM
compiler level for -d:evmc_enabled and -d:vm2_enabled
