Update the admin. overview page

Author: dwdougherty

content/develop/ai/search-and-query/administration/overview.md

@@ -239,9 +239,23 @@ These are the pre-bundled scoring functions available in Redis:
 * 
     Identical to the default TFIDF scorer, with one important distinction:
 
-* **BM25**
+* **BM25STD (default)**
 
-    A variation on the basic TF-IDF scorer. See [this Wikipedia article for more information](https://en.wikipedia.org/wiki/Okapi_BM25).
+    A variation on the basic `TFIDF` scorer, see [this Wikipedia article for more info](https://en.wikipedia.org/wiki/Okapi_BM25).
+
+    The relevance score for each document is multiplied by the presumptive document score and a penalty is applied based on slop as in `TFIDF`.
+
+    {{ note }}
+    The `BM25` scorer was renamed `BM25STD` in Redis Open Source 8.4. `BM25` is deprecated.
+    {{ /note }}
+
+* **BM25STD.NORM**
+
+    A variation of `BM25STD`, where the scores are normalized by the minimum and maximum score.
+
+* **BM25STD.TANH**
+
+    A variation of `BM25STD.NORM`, where the scores are normalised by linear function `tanh(x)`. `BMSTDSTD.TANH` can take an optional argument, `BM25STD_TANH_FACTOR Y`, which is used to smooth the function and the score values. The default value for `Y` is 4.
 
 * **DISMAX**