Fixes + sign formatting in deprecations page (#1192)

In the following place, the `+` sign needs to be escaped in order to go
out of the previous context to render correctly


![image](https://github.com/user-attachments/assets/9629c7b3-12a1-4b9e-94fa-c9e3e604f511)

Author: ikwattro

modules/ROOT/pages/deprecations-additions-removals-compatibility.adoc

@@ -297,7 +297,7 @@ label:deprecated[]
 ----
 ... + n:A&B\|C
 ----
-a| Using an unparenthesized label expression predicate as the right-hand side operand of `+` is deprecated.
+a| Using an unparenthesized label expression predicate as the right-hand side operand of `\+` is deprecated.
 Parenthesize the label expression predicate on the right-hand side of `+`: `... + (n:A)`.
 
 a|