feature #5595 Improve humanize filter documentation (bocharsky-bw)

This PR was submitted for the 2.7 branch but it was merged into the 2.3 branch instead (closes #5595).

Discussion
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Improve humanize filter documentation

Add processing camelCase text behavior description

Commits
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18610a4 Improve humanize filter documentation

Author: wouterj

reference/twig_reference.rst

@@ -380,7 +380,8 @@ humanize
     **type**: ``string``
 
 Makes a technical name human readable (i.e. replaces underscores by spaces
-and capitalizes the string).
+or transforms camelCase text like ``helloWorld`` to ``hello world``
+and then capitalizes the string).
 
 trans
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