Use plain text instead of latexmath

As latexmath is not rendered, using plain text instead

Closes #37718

docs/reference/query-dsl/script-score-query.asciidoc

@@ -53,7 +53,7 @@ rewriting equivalent functions of your own, as these functions try
 to be the most efficient by using the internal mechanisms.
 
 ===== rational
-latexmath:[rational(value,k) = value/(k + value)]
+`rational(value,k) = value/(k + value)`
 
 [source,js]
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@@ -64,7 +64,7 @@ latexmath:[rational(value,k) = value/(k + value)]
 // NOTCONSOLE
 
 ===== sigmoid
-latexmath:[sigmoid(value, k, a) = value^a/ (k^a + value^a)]
+`sigmoid(value, k, a) = value^a/ (k^a + value^a)`
 
 [source,js]
 --------------------------------------------------