Update release manual

See merge request frama-c/frama-c!4831

import zinc fine-tuning into master

[wp/ivette] print CE models

See merge request frama-c/frama-c!4833

[cabs2cil] do not crash on empty unions

Closes #1344

See merge request frama-c/frama-c!4799

[cabs] Add attributes in NOP statement for GCC

See merge request frama-c/frama-c!4775

[libc] Miscellaneous functions to be able to parse coreutils' sort.c in OSCS

See merge request frama-c/frama-c!4781

For now we ignore "unused" label attribute, because the current mecanism
does not support different attributes with the same name : "unused" can
be a label attribute or a function attribute.