docs: add adr to provide no support for in-place microvm updates

[jmickey]

What this PR does / why we need it:

Add ADR detailing the decision to not provide support for any in-place updates to running MicroVMs. See #234 for discussion related to this ADR.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #193

[codecov-commenter]

Codecov Report

Merging #252 (fa3dafd) into main (fe9bb9f) will decrease coverage by 15.52%.
The diff coverage is 41.78%.

@@             Coverage Diff             @@
##             main     #252       +/-   ##
===========================================
- Coverage   55.81%   40.29%   -15.53%     
===========================================
  Files          44       46        +2     
  Lines        2012     2169      +157     
===========================================
- Hits         1123      874      -249     
- Misses        781     1236      +455     
+ Partials      108       59       -49     

Impacted Files	Coverage Δ
core/application/commands.go	71.66% <ø> (+2.70%)	⬆️
core/application/reconcile.go	0.00% <ø> (ø)
core/models/vmid.go	90.24% <ø> (ø)
core/models/volumes.go	0.00% <ø> (ø)
core/steps/microvm/delete.go	100.00% <ø> (ø)
core/steps/runtime/dir_create.go	73.07% <ø> (ø)
core/steps/runtime/dir_delete.go	81.81% <ø> (ø)
core/steps/runtime/initrd_mount.go	100.00% <ø> (ø)
core/steps/runtime/kernel_mount.go	100.00% <ø> (ø)
infrastructure/containerd/content.go	0.00% <0.00%> (-100.00%)	⬇️
... and 37 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9cde2a1...fa3dafd. Read the comment docs.