[Suggestion]: Allow nesting verbatim ranged tags by using multiple `@` prefix

[boltlessengineer]

Currently in v1 spec, we cannot put @end\n inside verbatim ranged tag.

Makes it hard to write a norg document explaining norg syntax.
We do have |example to safely put @end\n inside a codeblock, but it's still hacky way to do that. It requires its content to be valid norg syntax and we cannot put |end inside it.

Suggestion

Allow user to use multiple @ prefix. Both starting and prefix should have same amount of prefix characters so we can put any lines inside a codeblock.

@@code

code block with `@end\n` in it.

@code
@end
`--- this won't close the codeblock starting from `@@code\n`

,--- only `end\n` with same amount of `@` prefix can close the codeblock.
@@end