add reproducible tarballs to the enhancements of EasyBuild v5

docs/easybuild-v5/enhancements.md

@@ -6,6 +6,7 @@ Various significant enhancements are included in EasyBuild v5.0, including:
 
 * [`run_shell_cmd` function][run_shell_cmd]
 * [Granular exit codes][granular_exit_codes]
+* [Reproducible tarballs][reproducible_tarballs]
 
 ---
 
@@ -25,3 +26,17 @@ checksum check. The full list of exit codes is defined in the class
 EasyBuild will always return its own exit codes on termination. Other exit
 codes from external processes executed through `run_shell_cmd` or HTTP response
 status codes are reported in the corresponding logs.
+
+## Reproducible tarballs { : #reproducible_tarballs}
+
+EasyBuild can now generate reproducible tarballs of sources downloaded from Git
+repositories. This means that the contents of sources obtained by cloning Git
+repositories will be consistent across different systems and across time,
+allowing to reliably validate those sources with checksums. EasyBuild follows
+the [archival guidelines from reproducible-builds.org](https://reproducible-builds.org/docs/archives/) 
+to generate reproducible tarballs.
+
+This new feature does not apply to sources cloned with `keep_git_dir` enabled.
+Including the `.git` folder in the sources is inherently time-dependent as it
+contains information about the clone action itself, which hinders the creation
+of a reproducible tarball.