document specific firefox issues

README.md

@@ -16,6 +16,7 @@ We can choose the urls on which the modifications applies by modifying the url p
 - The url pattern must follow the syntaxe define by https://developer.chrome.com/extensions/match_patterns
 - Putting an empty string on the field will select all urls
 - It's possible to select mutliple url patterns using semicolon(;) separator
+- It's not possible to define a specific port number https://stackoverflow.com/questions/11425591/match-port-in-chrome-extension-pattern
 
 To save and apply the modification , you need to click on the save button
 
@@ -25,13 +26,21 @@ It's possible to:
 
 The extension can be start and stop via the button on the top right.
 
-The rules are active in private window mode but you can't use the configuration window in this mode.
+Firefox Specific issues :
+- The rules are active in private window mode but you can't use the configuration window in this mode.
+- If  you check "never remember history" in firefox settings, the configuration will be lost when firefox exit.
+- According to the version of Firefox, the addition of a new header behaves differently. In the latest version, when you choose the "add" action and the header exist, it appends the value, while in the old version, it replaces it. If you want to modify an exiting header, you should use "modify" instead of "add"
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 The option button permits to :
 - Activate debug mode: show detail log messages in the extension debugging console of the browser.
 - Show comments : show comments field on the config panel 
 - Filter URL per rules : activate the possiblity to filter url for each rules on the config panel, the header field will be modify only if the url contains the configurated value.
 
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 The code is opensource under Mozilla Public License 2.0