Use Doctum instead of Sami (#761)

* Use Doctum instead of Sami

- Fix .gitignore
- Move the process to docs
- Add .gitattributes

* Fix the symfony/process versions after sami was removed

Used the maximum version of 2.x and forced 3.3 before deprecation in 3.4

docs/doctum.php

@@ -0,0 +1,15 @@
+<?php
+
+use Doctum\Doctum;
+use Symfony\Component\Finder\Finder;
+
+$iterator = Finder::create()
+    ->files()
+    ->name('*.php')
+    ->in(__DIR__.'/../src/');
+
+return new Doctum($iterator, [
+    'title'                => 'PHP-FFMpeg API',
+    'build_dir'            => __DIR__.'/source/API/API',
+    'cache_dir'            => __DIR__.'/source/API/API/cache',
+]);

docs/generate-docs.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+set -e
+
+SELF_DIR=$(dirname $0)
+cd ${SELF_DIR}
+
+rm -f doctum.phar
+rm -f doctum.phar.sha256
+
+# Download the latest (5.1.x) release if the file does not exist
+# Remove it to update your phar
+curl -o doctum.phar https://doctum.long-term.support/releases/5.1/doctum.phar
+curl -o doctum.phar.sha256 https://doctum.long-term.support/releases/5.1/doctum.phar.sha256
+
+sha256sum --strict --check doctum.phar.sha256
+rm doctum.phar.sha256
+
+# You can fetch the latest (5.1.x) version code here:
+# https://doctum.long-term.support/releases/5.1/VERSION
+
+
+# Show the version to inform users of the script
+php doctum.phar --version
+php doctum.phar update --force --ignore-parse-errors doctum.php -v