Escape the bare <- in a heading: MDX reads it as JSX and the build dies

`processPlatformCommit` #12929 failed on the push: Docusaurus compiles the
Markdown as MDX, and `## State changes (<-, NEW, DELETE)` gives
"Unexpected character `-` (U+002D) before name" from
micromark-extension-mdx-jsx — a `<` followed by anything that is not a
valid tag name aborts the whole site build. Backticks make it literal.

Scanned both branches for the same shape outside code fences: these two
headings were the only real ones; the other two hits are inside a backtick
span that wraps to the next line.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012YrYJtJ6hR2qJsk7FxjTjW

Author: 2 people

docs/brief/en/Brief_actions.md

@@ -3,7 +3,7 @@ slug: "/Brief_actions"
 title: 'Brief: actions'
 ---
 
-## State changes (<-, NEW, DELETE)
+## State changes (`<-`, NEW, DELETE)
 
 The [`CHANGE` operator](../language/CHANGE_operator.md) writes a value into a changeable property, the [`NEW` operator](../language/NEW_operator.md) adds an [object](../paradigm/New_object_NEW.md) of a concrete class, and the [`DELETE`](../language/DELETE_operator.md) and [`CHANGECLASS`](../language/CHANGECLASS_operator.md) operators delete an object or move it to another class:
 

docs/brief/ru/Brief_actions.md

@@ -3,7 +3,7 @@ slug: "/Brief_actions"
 title: 'Brief: действия'
 ---
 
-## Изменение состояния (<-, NEW, DELETE)
+## Изменение состояния (`<-`, NEW, DELETE)
 
 [Оператор `CHANGE`](../language/CHANGE_operator.md) пишет значение в изменяемое свойство, [оператор `NEW`](../language/NEW_operator.md) добавляет [объект](../paradigm/New_object_NEW.md) конкретного класса, операторы [`DELETE`](../language/DELETE_operator.md) и [`CHANGECLASS`](../language/CHANGECLASS_operator.md) удаляют объект или переводят его в другой класс: