Various minor changes to docs (#1468)

* Various minor changes to docs

* Revert failOnRisk and failOnWarning

.gitattributes

@@ -2,3 +2,4 @@
 /tests export-ignore
 /.* export-ignore
 /phpunit.xml.dist export-ignore
+/UPGRADE.md

.gitignore

@@ -5,3 +5,4 @@ composer.lock
 .DS_Store
 .php_cs.cache
 .hg
+.phpunit.result.cache

README.md

@@ -97,7 +97,7 @@ See also the list of [contributors](https://github.com/Seldaek/monolog/contribut
 
 ### License
 
-Monolog is licensed under the MIT License - see the `LICENSE` file for details
+Monolog is licensed under the MIT License - see the [LICENSE](LICENSE) file for details
 
 ### Acknowledgements
 

phpunit.xml.dist

@@ -1,6 +1,11 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<phpunit bootstrap="tests/bootstrap.php" colors="true" beStrictAboutTestsThatDoNotTestAnything="false">
+<phpunit
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd"
+        bootstrap="tests/bootstrap.php" colors="true"
+        beStrictAboutTestsThatDoNotTestAnything="false"
+>
     <testsuites>
         <testsuite name="Monolog Test Suite">
             <directory>tests/Monolog/</directory>