Correct typos in chapter Placeholders and Nesting
Update chapter Placeholders and Nesting
Correct typo
Distinguish indexed and named placeholders
Add usage of {} placeholder
Fix nesting code examples
Updated Placeholders and Nesting (markdown)
Added chapter Placeholders and Nesting
v2
Added reference to "Escaping curly braces"
Added working samples
Updated Expressions and Nesting (markdown)