Update documentation

[w3stling]

Updated documentation with:

• Example for reading from file using file URI

List<Item> items = new RssReader().read("file:/path/to/file");
                                  .toList();

• Examples of sorting items by updated time

.sorted(ItemComparator.newestUpdatedItemFirst())
.sorted(ItemComparator.oldestUpdatedItemFirst())

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Test Results

 11 files   11 suites   34s ⏱️
301 tests 300 ✅ 1 💤 0 ❌
309 runs  308 ✅ 1 💤 0 ❌

Results for commit 1360872.