`%q{c}` after another string literal is parsed as RHS of modulo, `q`
method call with a block.

If someone looks at documention for strings,
I don't think escape sequences is what they look
for in majority of the cases.

Since https://github.com/ruby/ruby/commit/5e1001f754b34e1f0cc67563512c6036b6eb75ab, the string link is broken

Instead of changing the anchor reference, I changed the header directly,
to keep in line with other titles

Document details of escape sequences including line continuation.

[Bug #20518]