Land rapid7#9067, add doc for auxiliary/scanner/http/http_header

Land rapid7#9067

Author: wchen-r7

documentation/modules/auxiliary/scanner/http/http_header.md

@@ -0,0 +1,46 @@
+## Description
+
+This module shows HTTP Headers returned by the scanned systems.
+
+## Verification Steps
+
+1. Do: ```use auxiliary/scanner/http/http_header```
+2. Do: ```set RHOSTS [IP]```
+3. Do: ```set RPORT [PORT]```
+4. Do: ```run```
+
+## Scenarios
+
+**Running the scanner**
+
+```
+msf > use auxiliary/scanner/http/http_header 
+msf auxiliary(http_header) > show options
+
+Module options (auxiliary/scanner/http/http_header):
+
+   Name         Current Setting                                                        Required  Description
+   ----         ---------------                                                        --------  -----------
+   HTTP_METHOD  HEAD                                                                   yes       HTTP Method to use, HEAD or GET (Accepted: GET, HEAD)
+   IGN_HEADER   Vary,Date,Content-Length,Connection,Etag,Expires,Pragma,Accept-Ranges  yes       List of headers to ignore, seperated by comma
+   Proxies                                                                             no        A proxy chain of format type:host:port[,type:host:port][...]
+   RHOSTS                                                                              yes       The target address range or CIDR identifier
+   RPORT        80                                                                     yes       The target port (TCP)
+   SSL          false                                                                  no        Negotiate SSL/TLS for outgoing connections
+   TARGETURI    /                                                                      yes       The URI to use
+   THREADS      1                                                                      yes       The number of concurrent threads
+   VHOST                                                                               no        HTTP server virtual host
+
+msf auxiliary(http_header) > set RHOSTS 192.168.56.101
+RHOSTS => 192.168.56.101
+msf auxiliary(http_header) > run
+
+[+] 192.168.56.101:80    : CONTENT-TYPE: text/html
+[+] 192.168.56.101:80    : SERVER: Apache/2.2.8 (Ubuntu) DAV/2
+[+] 192.168.56.101:80    : X-POWERED-BY: PHP/5.2.4-2ubuntu5.10
+[+] 192.168.56.101:80    : detected 3 headers
+[*] Scanned 1 of 1 hosts (100% complete)
+[*] Auxiliary module execution completed
+msf auxiliary(http_header) > 
+
+```