Small grammar fixes.
docs: eliminate usage of %s

I made one example slightly more complicated, but documentation should
show best practices rather than mislead to vulnerabilities.
Merge branch 'master' into doc-vulnerabilites

Conflicts:
	docs/tutorial.rst
Merge pull request #533 from michael-k/doc-vulnerabilites

docs: eliminate usage of %s
fix #529: Disable reverse DNS lookups for default server logs.
Merge pull request #509 from gabeio/patch-1

Small grammar fixes.