Added a comment

doc/forum/Using_reverse_proxy__59___base_URL_is_http_instead_of_https/comment_4_db726bc81ec5feac76d17ea81f0f80a5._comment

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+[[!comment format=mdwn
+ username="amcalvo"
+ ip="78.53.114.169"
+ subject="comment 4"
+ date="2014-05-05T21:56:36Z"
+ content="""
+A correction to the above comment, one needs activate multiple replacements:
+
+~~~
+        sub_filter 'http://example.com' 'https://example.com';
+        sub_filter_once off;
+~~~
+"""]]