Fixed typo in summation

This release fixes a typo of an invalid index in the summation in a formula in section §19.3 Smoothing Using Orthogonal Functions.

Spotted by Carsten Oppitz.

Small title page update

The exact document version is now visible directly on the title page.

First release

This first release represents a stable snapshot of the probability and statistics cookbook after 5 years of version control. From now on, the development switches to a variant of semantic versioning:

• The major version changes when adding a new section or topic.
• The minor version changes for non-trivial fixes, corrections, or improvements.
• The patch version changes for trivial fixes, such as typos in text or formulas.

After having removed the clumsy translation infrastructure, contributing becomes hopefully easier as well.

Big thanks to all the contributors so far!