docs: Update docs for 'filter by function' accessing query properties

docs/Introduction.md

@@ -13,7 +13,7 @@ _In recent [releases](https://github.com/obsidian-tasks-group/obsidian-tasks/rel
     Move the older ones down to the top of the comment block below...
 -->
 
-- X.Y.Z: 🔥 Enable [[Custom Grouping|custom grouping]] to use [[Query Properties|query properties]] directly - no placeholders required.
+- X.Y.Z: 🔥 Enable [[Custom Filters|custom filters]] and [[Custom Grouping|custom grouping]] to use [[Query Properties|query properties]] directly - no placeholders required.
 
 <!--
 - 5.0.0: 🔥 Add [[Line Continuations|line continuations]].

docs/Queries/Filters.md

@@ -1137,6 +1137,12 @@ Since Tasks 4.2.0, **[[Custom Filters|custom filtering]] by file path** is now p
 
 In Tasks 4.8.0 `task.file.pathWithoutExtension` was added.
 
+Since Tasks X.Y.Z, the query's file path can be used conveniently in custom filters:
+
+- `query.file.path` or
+- `query.file.pathWithoutExtension`
+- Useful reading: [[Query Properties]].
+
 <!-- placeholder to force blank line before included text --><!-- include: CustomFilteringExamples.test.file_properties_task.file.path_docs.approved.md -->
 
 ```javascript
@@ -1181,6 +1187,11 @@ The `root` is the top-level folder of the file that contains the task, that is,
 
 Since Tasks 4.2.0, **[[Custom Filters|custom filtering]] by root folder** is now possible, using `task.file.root`.
 
+Since Tasks X.Y.Z, the query's file root can be used conveniently in custom filters:
+
+- `query.file.root`
+- Useful reading: [[Query Properties]].
+
 <!-- placeholder to force blank line before included text --><!-- include: CustomFilteringExamples.test.file_properties_task.file.root_docs.approved.md -->
 
 ```javascript
@@ -1219,6 +1230,11 @@ This is the `folder` to the file that contains the task, which will be `/` for f
 
 Since Tasks 4.2.0, **[[Custom Filters|custom filtering]] by folder** is now possible, using `task.file.folder`.
 
+Since Tasks X.Y.Z, the query's file root can be used conveniently in custom filters:
+
+- `query.file.root`
+- Useful reading: [[Query Properties]].
+
 <!-- placeholder to force blank line before included text --><!-- include: CustomFilteringExamples.test.file_properties_task.file.folder_docs.approved.md -->
 
 ```javascript
@@ -1278,6 +1294,12 @@ Since Tasks 4.2.0, **[[Custom Filters|custom filtering]] by file name** is now p
 
 In Tasks 4.8.0 `task.file.filenameWithoutExtension` was added.
 
+Since Tasks X.Y.Z, the query's file name can be used conveniently in custom filters:
+
+- `query.file.filename` or
+- `query.file.filenameWithoutExtension`
+- Useful reading: [[Query Properties]].
+
 <!-- placeholder to force blank line before included text --><!-- include: CustomFilteringExamples.test.file_properties_task.file.filename_docs.approved.md -->
 
 ```javascript

docs/Scripting/Custom Filters.md

@@ -16,8 +16,9 @@ publish: true
 - The expression must evaluate to a `boolean`, so `true` or `false`.
 - There are loads of examples in [[Filters]].
   - Search for `filter by function` in that file.
-- Find all the supported tasks properties in [[Task Properties]] and [[Quick Reference]].
+- Find all the **supported tasks properties** in [[Task Properties]] and [[Quick Reference]].
   - A number of properties are only available for custom filters and grouping, and not for built-in grouping instructions.
+- Find all the **supported query properties** in [[Query Properties]].
 - Learn a bit about how expressions work in [[Expressions]].
 
 ## Custom filters introduction
@@ -40,12 +41,12 @@ The available task properties are also shown in the [[Quick Reference]] table.
 
 ### Available Query Properties
 
-The Reference section [[Query Properties]] shows all the query properties available for use via [[Placeholders]] in custom filters.
-
-Any placeholders in custom filters must be surrounded by quotes.
+The Reference section [[Query Properties]] shows all the query properties available for use in custom filters.
 
 > [!released]
-> Query properties and placeholders were introduced in Tasks 4.7.0.
+>
+> - Query properties and placeholders were introduced in Tasks 4.7.0, accessible via Placeholders.
+> - Direct access to Query properties was introduced in Tasks X.Y.Z.
 
 ### Expressions