Update routing.rst. Explain using url() v. path().
minor #3732 Update routing.rst. Explain using url() v. path(). (ackerman)

This PR was submitted for the 2.4 branch but it was merged into the 2.3 branch instead (closes #3732).

Discussion
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Update routing.rst. Explain using url() v. path().

The original documentation seemed to imply that, when generating absolute URLs from a template, the argument TRUE should be supplied to the url() method. This change explains that in Twig, one uses the url() method to generate an absolute URL.

Commits
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6eac303 Update routing.rst. Explain using url() v. path().