Rename the member-level annotation prefix from !accessors: to !access:
to decouple it from the !generate-accessors struct-level annotation.

Until now, the !accessors:<value> member annotation was consumed only
by the accessor generator, and its name reflected that — it read as a
natural companion to the struct-level !generate-accessors annotation.

That one-to-one relationship is about to change. An upcoming
!generate-python struct-level annotation will also need to read the
same member annotations, both to drive the generated SWIG layer and to
validate consistency between the C and Python sides. The annotation is
no longer the private concern of the accessor generator.

Keeping the name !accessors: would make that relationship confusing:

  - The visual similarity to !generate-accessors suggests the member
    annotation is owned by accessor generation, when in fact multiple
    generators will consume it.
  - Readers (and future contributors adding more generators) would
    reasonably — but wrongly — assume the annotation is accessor
    specific and only relevant when !generate-accessors is set.

Renaming to !access: breaks that false association. The new name also
reads more naturally as English:

  char *name;  // !access:readonly
  char *addr;  // !access:none

vs.

  char *name;  // !accessors:readonly
  char *addr;  // !accessors:none

This patch is a pure rename with no behavioural change:

  - generate-accessors.py: update has_annotation() lookups and the
    docstring examples
  - private.h: rename all 47 member annotations
  - generate-accessors.md: update every example, table row and note;
    re-pad the affected table rows to preserve column alignment

Generator output (accessors.h / accessors.c / accessors.ld) is byte
identical before and after this commit.

Signed-off-by: Martin Belanger <[email protected]>
Assisted-by: Claude Opus 4.7 <[email protected]>

Replace the single-mode !access:<value> annotation with an orthogonal
two-axis spec:

  !access:read=<mode>,write=<mode>

where read and write are independent and each takes one of:
generated (generator emits the accessor), custom (hand-written
accessor in the public API, generator emits nothing), or none (no
accessor exists).  The same spec is accepted at the struct level via
!generate-accessors:read=<mode>,write=<mode>, with per-axis
inheritance from the struct-level default to member-level overrides.

The new model lets downstream consumers (the Python-binding generator,
the nvme.i consistency check) distinguish "no accessor" from
"hand-written accessor", and cleanly expresses mixed cases such as
"generated getter + hand-written setter" that the old one-dimensional
annotation could not name.  This is a clean break: the old :none /
:readonly / :writeonly / :readwrite tokens are no longer recognised.

See libnvme/tools/generator/generate-accessors.md for the full syntax,
inheritance rules, and examples.

All 47 !access: annotations in private.h are updated accordingly.  The
regenerated accessors.{h,c,ld} are byte-identical to the pre-change
baseline.

Signed-off-by: Martin Belanger <[email protected]>
Assisted-by: Claude Opus 4.7 <[email protected]>