diff --git a/CHANGELOG.md b/CHANGELOG.md
index d6ced05..397be1e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## `0.4.0`
+- support for image matching (issue #16, *alpha* feature)
+- tag filtering with *semver* and *regex* (issue #22, *alpha* feature)
+- support token based authentication for *Google Artifact Registry* (issue #51)
+- doc updates & corrections
+
 ## `0.3.6`
 - added container image based on *Ubuntu 20.04* (issue #47)
 
diff --git a/README.md b/README.md
index 81d638c..f55fb93 100644
--- a/README.md
+++ b/README.md
@@ -104,7 +104,7 @@ tags:
 
 This would sync all tags describing versions equal to or larger than `1.31.0`, but lower than `1.31.9`, via the `semver:` filter. The `regex:` filter additionally syncs any `1.26.`x image with suffix `-glibc`, `-uclibc`, or `-musl`. Finally, the verbatim tags `1.29.4` and `latest` are also synced.
 
-Note that the tags of an image need to conform to the *semver* specification *2.0.0* in order to be considered during filtering. The implementation uses the [blang/semver](https://github.com/blang/semver) lib. Have a look at their page or [the GoDoc](https://pkg.go.dev/github.com/blang/semver/v4) for more info on how to write *semver* filter expressions. Semver filtering tolerates and handles tags starting with a `v` prefix. Semver filter expressions however must not use a `v` prefix. Regex filters use standard *Go* regular expressions. When the first non-whitespace character after `regex:` is `!`, the filter will use inverted match. Keep in mind that when a regex contains a backslash, you need to place it inside single quotes to keep the YAML valid.
+Note that tag filtering is still an *alpha* feature. Also, the tags of an image need to conform to the *semver* specification *2.0.0* in order to be considered during filtering. The implementation uses the [blang/semver](https://github.com/blang/semver) lib. Have a look at their page or [the GoDoc](https://pkg.go.dev/github.com/blang/semver/v4) for more info on how to write *semver* filter expressions. Semver filtering tolerates and handles tags starting with a `v` prefix. Semver filter expressions however must not use a `v` prefix. Regex filters use standard *Go* regular expressions. When the first non-whitespace character after `regex:` is `!`, the filter will use inverted match. Keep in mind that when a regex contains a backslash, you need to place it inside single quotes to keep the YAML valid.
 
 You can add multiple `semver:` and `regex:` filters under `tags`. Note however that the filters are simply ORed, i.e. a tag is synced if it satisfies at least one of the items under `tags`, be it semver, regex, or verbatim. So this is not a filter chain. Also, no sanity checks are done on the filters, so care must be taken to avoid competing or contradicting filters that select all or nothing at all.