Improve README and issue template (#91)

Author: Minishlink

ISSUE_TEMPLATE.md

@@ -26,12 +26,12 @@ helps with diagnosing problems quicker.
 
 - [ ] Chrome
 - [ ] Firefox
+- [ ] Firefox for Mobile
 - [ ] Opera for Android
 - [ ] Samsung Internet Browser
 - [ ] Other
 
-> Please list the browsers you are have tested this, including the version
-> of the browser (i.e. Chrome Beta, Firefox Beta etc).
+> Please specify the versions (i.e. Chrome Beta, Firefox Beta etc).
 
 # Problem
 

README.md

@@ -4,21 +4,25 @@
 [![Build Status](https://travis-ci.org/web-push-libs/web-push-php.svg?branch=master)](https://travis-ci.org/web-push-libs/web-push-php)
 [![SensioLabsInsight](https://insight.sensiolabs.com/projects/d60e8eea-aea1-4739-8ce0-a3c3c12c6ccf/mini.png)](https://insight.sensiolabs.com/projects/d60e8eea-aea1-4739-8ce0-a3c3c12c6ccf)
 
+WebPush can be used to send notifications to endpoints which server delivers Web Push notifications as described in 
+the [Web Push protocol](https://tools.ietf.org/html/draft-thomson-webpush-protocol-00).
+As it is standardized, you don't have to worry about what server type it relies on.
+
+## Requirements
+* PHP 5.6
+  * gmp
+  * mbstring
+  * curl
+  * openssl
+
+PHP 7.1 is recommended for better performance.
+
 ## Installation
 Use [composer](https://getcomposer.org/) to download and install the library and its dependencies.
 
 `composer require minishlink/web-push`
 
 ## Usage
-WebPush can be used to send notifications to endpoints which server delivers web push notifications as described in 
-the [Web Push protocol](https://tools.ietf.org/html/draft-thomson-webpush-protocol-00).
-As it is standardized, you don't have to worry about what server type it relies on.
-
-Notifications with payloads are supported with this library on Firefox 46+ and Chrome 50+.
-
-You'll need at least PHP 5.6 with the following extensions enabled: gmp, mbstring, curl, openssl.
-PHP 7.1 is recommended for much better performance.
-
 ```php
 <?php
 
@@ -176,6 +180,8 @@ $res = array(
 );
 ```
 
+Firefox errors are listed in the [autopush documentation](https://autopush.readthedocs.io/en/latest/http.html#errors).
+
 ### Payload length, security, and performance
 Payloads are encrypted by the library. The maximum payload length is theoretically 4078 bytes (or ASCII characters).
 For [compatibility reasons](mozilla-services/autopush/issues/748) though, your payload should be less than 3052 bytes long.
@@ -270,9 +276,18 @@ Make sure to require Composer's [autoloader](https://getcomposer.org/doc/01-basi
 require __DIR__ . '/path/to/vendor/autoload.php';
 ```
 
+### I must use PHP 5.4 or 5.5. What can I do?
+You won't be able to send any payload, so you'll be only able to use `sendNotification($endpoint)`.
+Install the libray with `composer` using `--ignore-platform-reqs`.
+The workaround for getting the payload is to fetch it in the service worker ([example](https://github.com/Minishlink/physbook/blob/2ed8b9a8a217446c9747e9191a50d6312651125d/web/service-worker.js#L75)). 
+
 ### I lost my VAPID keys!
 See [issue #58](https://github.com/web-push-libs/web-push-php/issues/58).
 
+### I'm using Firebase push notifications, how do I use this library?
+This library is not designed for Firebase push notifications.
+You can still use it for your web projects (for standard WebPush notifications), but you should forget any link to Firebase while using the library.
+
 ### I need to send notifications to native apps. (eg. APNS for iOS)
 WebPush is for web apps.
 You need something like [RMSPushNotificationsBundle](https://github.com/richsage/RMSPushNotificationsBundle) (Symfony).