Placeholder(s) for release notes text

## Background
The possibility to have patterns how the release note entries look like is great,but not all aspects are yet configurable.

## Feature
Add placeholders for release note entry and releasse note entry line.
If release note entry is not present, use title instead.

## Example
Template: `{number} _{title}_ {developed-by}\n{release-note-entry}`
#33 _Simplify working with result row_ @benedeki
- Added function execute
- Added function resultSet

Template: ` _{release-note-line-entry}_ {developed-by} in {pr}`
_Added function execute_ developed by @benedeki in #34
_Added function resultSet_ developed by @benedeki in #34