[DOC] Add changelog entry

Signed-off-by: Lydia Buntrock <lydia.buntrock@fu-berlin.de>

CHANGELOG.md

@@ -32,6 +32,8 @@ If possible, provide tooling that performs the changes, e.g. a shell-script.
 
 * Added `seqan3::phred94`, a quality type that represents the full Phred Score range (Sanger format) and is used for
   PacBio Phred scores of HiFi reads ([\#2290](https://github.com/seqan/seqan3/pull/2290)).
+* Deprecated `seqan3::phred68legacy`. Use `seqan3::phred68solexa` instead.
+  ([\#...](https://github.com/seqan/seqan3/pull/...)).
 
 #### Argument Parser
 
@@ -60,7 +62,7 @@ If possible, provide tooling that performs the changes, e.g. a shell-script.
   ([\#2340](https://github.com/seqan/seqan3/pull/2340), [\#2380](https://github.com/seqan/seqan3/pull/2380),
   [\#2389](https://github.com/seqan/seqan3/pull/2389))
 * Deprecated `seqan3::field::seq_qual`. Use `seqan3::fiel::seq` and `seqan3::field::qual` instead.
-  ([\#2379](https://github.com/seqan/seqan3/pull/2379)). Check out 
+  ([\#2379](https://github.com/seqan/seqan3/pull/2379)). Check out
   [SeqAn3 Cookbook - Write Record](https://docs.seqan.de/seqan/3.0.3/cookbook.html)
   for usage.
 
@@ -112,8 +114,8 @@ If possible, provide tooling that performs the changes, e.g. a shell-script.
 
 ## API changes
 
-Most of our API or header file changes will trigger a deprecation warning to let you know if something changed and, if 
-applicable, when it will be removed. We recommend upgrading version-by-version to check whether you need to change code. 
+Most of our API or header file changes will trigger a deprecation warning to let you know if something changed and, if
+applicable, when it will be removed. We recommend upgrading version-by-version to check whether you need to change code.
 You can either directly check the reported code or verify with our documentation how the new API should be used.
 
 For a complete list of behavioural changes in our public and internal API, you can consult our API stability