[AG-49140] Updated HTML filtering syntax for AdGuard Browser Extension (#808)

Author: kurrx

docs/general/ad-filtering/create-own-filters.md

@@ -4261,6 +4261,8 @@ The syntax with an optional `value` in the attributes is supported by AdGuard fo
 
 ### Syntax
 
+Syntax supported by AdGuard for Windows, AdGuard for Mac, AdGuard for Android, AdGuard for Linux with CoreLibs, and AdGuard Browser Extension prior to v5.2:
+
 ```text
      selector = [tagName] [attributes] [pseudoClasses]
    combinator = ">"
@@ -4278,6 +4280,24 @@ pseudoClasses = pseudoClass *pseudoClass
 - **`pseudoArgs`** — the arguments of a function-style pseudo-class.
 - **`combinator`** — an operator that works similarly to the [CSS child combinator](https://developer.mozilla.org/en-US/docs/Web/CSS/Child_combinator): that is, the `selector` on the right of the `combinator` will only match an element whose direct parent matches the `selector` on the left of the `combinator`.
 
+Syntax supported by AdGuard Browser Extension v5.3 or later:
+
+```text
+         rule = [domains] "$$" selector
+      domains = [domain0, domain1[, ...[, domainN]]]
+```
+
+- **`selector`** — [CSS selector](https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Getting_Started/Selectors), defines the element(s) to be removed from the HTML code before the page is loaded.
+- **`domains`** — domain restriction for the rule. Same principles as in [element hiding rule syntax](#cosmetic-elemhide-rules).
+
+:::caution Limitations
+
+The following limitations apply to AdGuard Browser Extension v5.3 and later:
+
+- Pseudo-elements (e.g., `::before`, `::after`) are not supported, as they are not applicable in the context of HTML filtering.
+
+:::
+
 ### Examples
 
 **HTML code:**
@@ -4343,6 +4363,8 @@ $$script[tag-content="banner"]
 
 The `tag-content` special attribute must not appear in a selector to the left of a `>` combinator.
 
+This limitation does not apply to AdGuard Browser Extension v5.3 or later.
+
 :::
 
 #### `wildcard`
@@ -4367,6 +4389,8 @@ It checks if the element code contains the two consecutive substrings `banner` a
 
 The `wildcard` special attribute must not appear in a selector to the left of a `>` combinator.
 
+This limitation does not apply to AdGuard Browser Extension v5.3 or later.
+
 :::
 
 #### `max-length`
@@ -4395,6 +4419,8 @@ This rule will remove all the `div` elements, whose code contains the substring
 
 The `max-length` special attribute must not appear in a selector to the left of a `>` combinator.
 
+This limitation does not apply to AdGuard Browser Extension v5.3 or later.
+
 :::
 
 #### `min-length`
@@ -4419,6 +4445,8 @@ This rule will remove all the `div` elements, whose code contains the substring
 
 The `min-length` special attribute must not appear in a selector to the left of a `>` combinator.
 
+This limitation does not apply to AdGuard Browser Extension v5.3 or later.
+
 :::
 
 ### Pseudo-classes {#html-filtering-rules--pseudo-classes}
@@ -4445,7 +4473,7 @@ or
 
 :::info Compatibility
 
-The `:contains()` pseudo-class is supported by AdGuard for Windows, AdGuard for Mac, AdGuard for Android, and AdGuard for Linux with [CoreLibs] v1.13 or later.
+The `:contains()` pseudo-class is supported by AdGuard for Windows, AdGuard for Mac, AdGuard for Android, AdGuard for Linux with [CoreLibs] v1.13 or later, and AdGuard Browser Extension v5.3 or later.
 
 :::
 
@@ -4455,6 +4483,8 @@ Requires that the inner HTML of the element contains the specified text or match
 
 A `:contains()` pseudo-class must not appear in a selector to the left of a `>` combinator.
 
+This limitation does not apply to AdGuard Browser Extension v5.3 or later.
+
 :::
 
 ### Exceptions