Fix some typos
Merge pull request #222 from winzou/security-fix

Fix some typos in security book
Fix typo in collection.rst

Fix typo in collection.rst
Fix typo
Fix typo in book/templating.rst
Merge pull request #225 from lucascourot/2.1

Fix typo
Merge pull request #224 from cedriclombardot/2.1

Fix typo in collection.rst