Update paragraph "using server variables in rewrite rules"

[CloudCees]

What is described in paragraph "using server variables in rewrite rules" is not correct. The information In the list about http headers is not correct. A dash in the http header is not converted to an underscore. It should be stated that de underscore from the condition input is converted to a dash. When the statement from the text was true, I could handle a HTTP header with an underscore in it.

[CloudCees]

~~I just found the page where it is correctly stated: https://docs.microsoft.com/en-us/iis/extensions/url-rewrite-module/url-rewrite-module-20-configuration-reference#accessing-response-headers-from-rewrite-rules~~

~~"All underscore ("_") symbols in the name are converted to dash symbols ("-")."~~

[lextm]

@Cezus You are wrong. This paragraph is talking about incoming requests, while the one you linked is about "responses".

[CloudCees]

@Cezus You are wrong. This paragraph is talking about incoming requests, while the one you linked is about "responses".

You are right, that article does not apply in this matter. But the problem I try to address is still valid. The problem is as following: https://stackoverflow.com/questions/52816655/how-can-url-rewrite-match-http-headers-with-underscores

[Rick-Anderson]

@John-Hart please review

[John-Hart]

@ning51 could you please verify this?

[Rick-Anderson]

@ning51 @John-Hart if this is an improvement, can I S&M. @ning51 can create an issue to track the suggestion.