Incomplete "Configuration" Wiki page

Nobody has claimed this yet.

According to git history a "group-blacklist" option is add for the "inmemory" Storage around 2 years ago. My testing shows that this is the only way to actually remove a consumer group from the returned list of consumer groups when calling "/v3/kafka/local/consumer".
Following is my suggestion for change of the Configuration.md file in the Wiki, as far as I understand one cannot make a PR for a Wiki page.

```

$ git diff
diff --git a/Configuration.md b/Configuration.md
index f857990..cf3fa84 100644
--- a/Configuration.md
+++ b/Configuration.md
@@ -131,6 +131,7 @@ expire-group=604800
workers=20
min-distance=1
group-whitelist=".*"
+group-blacklist="^not-this-group$"

| Key | Value Type | Required | Default Value | Description |
| --- | ---------- | -------- | ------------- | ----------- |
@@ -139,7 +140,8 @@ group-whitelist=".*"
| expire-group | integer | no | 604800 | The number of seconds after which a group will be purged if it has not committed offsets. |
| workers | integer | no | 20 | The number of worker goroutines to start up. This number can be increased to provide more parallelism in the storage module. |
| min-distance | integer | no | 0 | Coalesce offset commits that are more frequent than this number of seconds. Used with the intervals configuration, this can be used to set a minimum time for the offset window (10 offsets x 15s = 150s minimum window). |
-| group-whitelist | string (regex) | no | (empty) | If specified, ignore data for groups that do not match the regular expression. |
+| group-whitelist | string (regex) | no | (empty) | If specified, ignore data for groups that DO NOT match the regular expression. |
+| group-blacklist | string (regex) | no | (empty) | If specified, ignore data for groups that MATCH the regular expression. This is processed after the whitelist (if specified). |
```

Open the Wiki's Configuration.md and review the existing group-whitelist entry alongside the inmemory storage configuration described in the issue. Add the group-blacklist option and clarify both whitelist and blacklist descriptions, including their processing order; the updated Wiki page matching the proposed diff is done.

Written by the indexing model from the issue text.