[MISC] Add changelog entry

CHANGELOG.md

@@ -132,10 +132,14 @@ regression test suite and patches at https://github.com/seqan/seqan3/tree/master
   * Use `seqan3::phred42::assign_phred()` or `seqan3::operator""_phred42` instead of `seqan3::phred42(phred_type)`.
   * Use `seqan3::phred63::assign_phred()` or `seqan3::operator""_phred63` instead of `seqan3::phred63(phred_type)`.
   * Use `seqan3::phred94::assign_phred()` or `seqan3::operator""_phred94` instead of `seqan3::phred94(phred_type)`.
-  * Use `seqan3::phred68legacy::assign_phred()` or `seqan3::operator""_phred68legacy` instead of 
+  * Use `seqan3::phred68legacy::assign_phred()` or `seqan3::operator""_phred68legacy` instead of
     `seqan3::phred68legacy(phred_type)`.
 * Renamed `seqan3::quality_base` to `seqan3::phred_base`
   ([\#2539](https://github.com/seqan/seqan3/pull/2539)).
+* Added the `seqan3::literals` namespace containing all literals. This adds the option to use
+  `using namespace seqan3::literals` to import literal operators. The old way of explicitly importing specific
+  operators via `using seqan3::operator""_{dna4, rna4, ...}` is not affected by this change
+  ([\#2568](https://github.com/seqan/seqan3/pull/2568)).
 
 #### Argument Parser