Add lessons learned from LWG issues processing meeting

[mhoemmen]

@dsunder @mhoemmen Per request by @crtrott

[dsunder]

• [ ] code font boolean expressions need to be written in words or the statements need to include the words "is true". For example, the boolean expression rank()==N could be expressed as

  • rank() == N is true
  • rank() equals N.

• [ ] Change most of the "Returns:" to "Effects: Equivalent to code"

• [ ] Remove "shall" except for user requirements

• [ ] replace typename with class in template params

• [ ] correct italic and code font

• [ ] use ISO spacing in code

• [ ] review grammer

Add concepts, potentially exposition only (see Range TS), for the following template parameters (use kabob case for exposition only concepts

• [ ] MDSpanElement (mdspan-element)
• [ ] MDSpanExtents (mdspan-extents)
• [ ] MDSpanLayout (mdspan-layout)
• [ ] MDSpanAccessor (mdspan-accessor)
• [ ] MDSpanSubSpanSliceSpecifier (mdspan-subspan-slice-specifier)

[mhoemmen]

Does mdspan do any {}-initialization? We need to watch out for that too.

[mhoemmen]

The library specification uses a typographical convention for naming requirements. Names in italic type that begin with the prefix Cpp17 refer to sets of well-defined expression requirements typically presented in tabular form, possibly with additional prose semantic requirements. For example, Cpp17Destructible (Table 29) is such a named requirement. Names in constant width type refer to library concepts which are presented as a concept definition (Clause 12), possibly with additional prose semantic requirements. For example, Destructible (17.4.10) is such a named requirement.

[mhoemmen]

For loops need to be ISO spacing compliant. Ditto for less-than.