Carefully handle string literal with RAM

[ryanpatiency]

This example copy flash to ram, however, string literal is in .text region rather than .data region. Because the linker script put the .rodata region under the text region.

[jserv]

You should mention in program comments as well. Mention its explicit considerations and specifications.

[ryanpatiency]

Already

[jserv]

Additional information about string literal allocation is required in C comment. Use git rebase -i to rework the commits.

[ryanpatiency]

I add the comment directly on the github, illustrate WHY the variable exist and the behavior about LMA and VMA.