chore: Update README, LICENCE, and add code linting

.php-cs-fixer.dist.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+$header = <<<EOF
+This file is part of the "PHP Helpers: Command-line Functions" repository.
+
+Copyright 2019-2021 Alannah Kearney <hi@alannahkearney.com>
+
+For the full copyright and license information, please view the LICENCE
+file that was distributed with this source code.
+EOF;
+
+return (new PhpCsFixer\Config())
+    ->setUsingCache(true)
+    ->setRiskyAllowed(true)
+    ->setFinder(
+        (new PhpCsFixer\Finder())
+            ->files()
+            ->name('*.php')
+            ->in(__DIR__)
+            ->exclude(__DIR__.'/vendor')
+    )
+    ->setRules([
+        '@PSR2' => true,
+        '@Symfony' => true,
+        'is_null' => true,
+        'blank_line_before_statement' => ['statements' => ['continue', 'declare', 'return', 'throw', 'try']],
+        'cast_spaces' => ['space' => 'single'],
+        'header_comment' => ['header' => $header],
+        'include' => true,
+        'class_attributes_separation' => ['elements' => ['const' => 'one', 'method' => 'one', 'property' => 'one']],
+        'no_blank_lines_after_class_opening' => true,
+        'no_blank_lines_after_phpdoc' => true,
+        'no_empty_statement' => true,
+        'no_extra_blank_lines' => true,
+        'no_leading_import_slash' => true,
+        'no_leading_namespace_whitespace' => true,
+        'no_trailing_comma_in_singleline_array' => true,
+        'no_unused_imports' => true,
+        'no_whitespace_in_blank_line' => true,
+        'object_operator_without_whitespace' => true,
+        'phpdoc_align' => true,
+        'phpdoc_indent' => true,
+        'phpdoc_no_access' => true,
+        'phpdoc_no_package' => true,
+        'phpdoc_order' => true,
+        'phpdoc_scalar' => true,
+        'phpdoc_trim' => true,
+        'phpdoc_types' => true,
+        'psr_autoloading' => true,
+        'array_syntax' => ['syntax' => 'short'],
+        'declare_strict_types' => true,
+        'single_blank_line_before_namespace' => true,
+        'standardize_not_equals' => true,
+        'ternary_operator_spaces' => true,
+        'trailing_comma_in_multiline' => true,
+    ])
+;