As a general rule, `operator()` should be const-qualified.
The exceptions are few and far between.

I was actually looking for a Guideline on that subject;
I grepped for `operator()` and found that not only is there
no such Guideline yet, the doc actually contained these
places that (needlessly) violated the general rule.

Using `this` in a free function makes the program ill-formed;
it doesn't magically give you a `std::thread*`.

The comments were:
// ???Must we suffer CaMelcAse???
and
// ugly CaMeLcAsEvArIaBlE

* Use '<thing> template' i.s.o. 'template <thing>'

The word 'template' is often wrongly used as an adjective to the 'thing'
it becomes when instantiated.

* Expand succinct formulation for readability
Co-authored-by: NKristoffel Pirard <kristoffel.pirard@vanhool.com>

The rules NL.11 (Make literals readable) and NL.15 (Use spaces
sparingly) are placed in inverted order in the text flow, swap them.

"Make your code thread-safe" usually means "don't use global state."
Advice to replace global state with `thread_local` state is usually misguided.
https://quuxplusone.github.io/blog/2018/11/14/fiber-local-storage/

* Adjust the spacing for consistency

* Adjust the spacing for consistency-2

The _bad_ example wasn't annotated as such and a perfectly fine function
name was marked bad.

Annotate the example as bad and remove the misleading function name
annotation.

For some reason the trailing `e = 3` seemed more of a red flag
than anything else about this line. Let's imply that the programmer
is trying to make some constants for hexadecimal translation.

* dumb -> inefficient

* Actually detect negative sizes by following ES.106

And don't use senseless one letter names

* fix grammar
Co-Authored-By: NJohel Ernesto Guerrero Peña <johelegp@gmail.com>
Co-authored-by: NJohel Ernesto Guerrero Peña <johelegp@gmail.com>

new[] needs delete[]

Typo

* add SF.12

* add incscope to isocpp.dic to get the CI build to pass

* expand INCLUDES, update dictionary for the ci build to pass

* pr feedback

* in the same directory

* update based on feedback

* 3rd try

* PR feedback

* update lable

* Update CppCoreGuidelines.md

* Update CppCoreGuidelines.md

Changed the two anchors back (anchors need to stay stable and don't
display visibly anyway)
Switched "non-public" back to hyphernated (to use hyphenation
consistently)

* Add hyphens to words that begins with a non

* Remove hyphens in nonpublic

Added example to CP.61: Use an async() to spawn a concurrent task

* Casting away const isn't undefined behavior, but modifying a constant is

You can cast away `const` as much as you like, as long as you never write to variable.

* rewording for clarification