Update for version v5.0

Allow dashes/hyphens to appear in tags #168
Allow --period filtering by week and quarter #179
Relicense the specification #173
Introduce (optional) values for tags #169
Specify how to deal with invalid input #163

CHANGELOG.md

@@ -1,6 +1,17 @@
 # Changelog
 **Summary of changes of the command line tool**
 
+## v5.0
+- **[ META ]** Release the klog file format specification into the public domain
+  (under the CC0/OWFa dual license).
+  Read it here: https://github.com/jotaen/klog/blob/main/Specification.md
+- **[ FEATURE ]** Allow tags to (optionally) have values assigned to them,
+  e.g. `#ticket=1764` or `#type=work`. The values can be quoted if
+  they contain special characters: `#project="22/48.3"`.
+- **[ FEATURE / BREAKING ]** Allow hyphens (`-`) to appear in tags, e.g. `#home-office`.
+- **[ FEATURE ]** For the `--period` flag, additionally allow filtering
+  by quarter (`YYYY-Qq`, e.g. `2022-Q1`) and week (`YYYY-Www`, e.g. `YYYY-W34`).
+
 ## v4.0
 - **[ FEATURE ]** Allow summaries behind entries to be continued on
   the next line (with increased indentation level), e.g.: