MDL-66306 lib: upgrade moodle lib docs

lib/phpmailer/README_MOODLE.txt

@@ -1,31 +1,20 @@
-Description of PHPMailer 6.0.1 library import into Moodle
+Description of PHPMailer 6.0.7 library import into Moodle
 
 We now use a vanilla version of phpmailer and do our customisations in a
 subclass.
 
-When doing the import we remove directories/files:
-.github/
-.phan/
-docs/
-examples/
-src/OAuth.php
-src/POP3.php
-test/
-.gitattributes
-.gitignore
-.php_cs
-.scrutinizer.yml
-.travis.yml
-SECURITY.md
-UPGRADING.md
-composer.json
-get_oauth_token.php
-phpdoc.dist.xml
-travis.phpunit.xml.dist
+For more information on this version of PHPMailer, check out https://github.com/PHPMailer/PHPMailer/releases/tag/v6.0.7
+
+To upgrade this library:
+1. Download the latest release of PHPMailer in https://github.com/PHPMailer/PHPMailer/releases.
+2. Remove the lib/phpmailer/language folder. This will be replaced with language folder from the latest release.
+3. Extract the contents of the release archive to lib/phpmailer.
+4. Remove the following files that were extracted:
+   - composer.json
+   - get_oauth_token.php
+   - SECURITY.md
+   - src/OAuth.php
+   - src/POP3.php
+5. Update lib/thirdpartylibs.xml.
 
 Local changes (to verify/apply with new imports):
-
-- MDL-63967: PHP 7.3 compatibility.
-    lib/phpmailer/src/PHPMailer.php: FILTER_FLAG_HOST_REQUIRED is deprecated and
-    implied with FILTER_VALIDATE_URL. This was fixed upstream by
-    https://github.com/PHPMailer/PHPMailer/pull/1551

lib/thirdpartylibs.xml

@@ -95,7 +95,7 @@
     <location>phpmailer</location>
     <name>PHPMailer</name>
     <license>LGPL</license>
-    <version>6.0.1</version>
+    <version>6.0.7</version>
     <licenseversion>2.1</licenseversion>
   </library>
   <library>