polish documentation based on scrutinizer patches

apps/files_encryption/hooks/hooks.php

apps/files_encryption/lib/crypt.php

apps/files_encryption/lib/helper.php

apps/files_encryption/lib/keymanager.php

apps/files_encryption/lib/session.php

apps/files_encryption/lib/util.php

apps/files_encryption/tests/crypt.php

apps/files_encryption/tests/keymanager.php

apps/files_encryption/tests/util.php

apps/files_external/lib/amazons3.php

apps/files_external/lib/config.php

apps/files_external/lib/dropbox.php

apps/files_external/lib/google.php

apps/files_external/lib/irods.php

apps/files_external/lib/sftp.php

apps/files_external/lib/streamwrapper.php

apps/files_external/lib/swift.php

apps/files_external/lib/webdav.php

apps/files_sharing/lib/cache.php

apps/files_sharing/lib/permissions.php