make CBLD follow ACPERM rules (#238)

Close #229 by adding the
statement about following ACPERM rules.
I also reformatted the text into a list to make it easier to read.

src/insns/cbld_32bit.adoc

@@ -21,11 +21,18 @@ Encoding::
 include::wavedrom/cbld.adoc[]
 
 Description::
-Copy `cs2` to `cd` and set the tag to 1 if `cs1.tag` is set, `cs1` is not
-sealed, `cs2` 's permissions and bounds are equal to or a subset of `cs1` 's,
-`cs2` 's bounds are not malformed (see
-xref:section_cap_malformed[xrefstyle=short]), and all reserved bits in `cs2` 's
-metadata are 0; otherwise, copy `cs2` to `cd` and clear `cd` 's tag. <<CBLD>> is typically used alongside <<SCHI>> to build
+Copy `cs2` to `cd` and set `cd.tag` to 1 if
+
+. `cs1.tag` is set, and
+. `cs1` is not sealed, and
+. `cs2` 's permissions and bounds are equal to or a subset of `cs1` 's, and
+. `cs2` 's bounds are not malformed (see xref:section_cap_malformed[xrefstyle=short]), and
+. `cs2` 's permissions could have been legally produced by <<ACPERM>>, and
+. All reserved bits in `cs2` 's metadata are 0;
+
+Otherwise, copy `cs2` to `cd` and clear `cd` 's tag.
+
+<<CBLD>> is typically used alongside <<SCHI>> to build
 capabilities from integer values.
 
 NOTE: When `cs1` is `c0` this will set the tag to 0 and leave the metadata