Improve descriptions of rotm, rotmg, stdlib_srotm, stdlib_srotmg

[Beliavsky]

At https://stdlib.fortran-lang.org/lists/procedures.html the descriptions of rotm, rotmg, stdlib_srotm, stdlib_srotmg are in all upper case, inconsistent with the other descriptions and making them less readable. They are also too long and low-level. I assume the descriptions are generated automatically from the source code.