Most errors found with:
codespell -L cach,thst,odly,aslo,parm,parms,inpu,ges,prset,pevent,ptd,pring,valu,noo,noe,ned,inout,ro,siz,froms,nd,fo,singl,sart,multy,tthe,allong,ment,inate,nodel,tring,alse,ture,thi,wille,numer
Some more manually found (its -> it's)
c++20: Do not use apostrophe (e.g. can't) in unquoted #error message
- Use a Sphinx/Myst {include} directive to pull the text from all previous
RELEASE files into the output, which makes the website sidebar index work
properly.
- Exclude the RELEASE files from the files given to RTD to publish, they
aren't needed now and generate warnings if included.
- Updated the intro paragraph in all RELEASE files.
