vault: Fix released version number in various files

Author: claremacrae

resources/sample_vaults/Tasks-Demo/How To/Access properties in frontmatter.md

@@ -1,6 +1,6 @@
 # Access properties in frontmatter
 
-These examples work with Tasks X.Y.Z and later.
+These examples work with Tasks 7.7.0 and later.
 
 ## Accessing a custom property for grouping
 

resources/sample_vaults/Tasks-Demo/How To/Find tasks in notes with particular tag.md

@@ -2,7 +2,7 @@
 
 Suppose we wanted to find all tasks in notes that had a particular tag `#examples` in the frontmatter.
 
-Since Tasks X.Y.Z, this is now possible in Tasks queries:
+Since Tasks 7.7.0, this is now possible in Tasks queries:
 
 ```tasks
 filter by function task.file.property('tags').includes('#examples')

resources/sample_vaults/Tasks-Demo/How To/Reuse instructions across the vault.md

@@ -7,7 +7,7 @@ TQ_extra_instructions: |-
 ---
 # Reuse instructions across the vault
 
-These searches are for experimenting with, and understanding, the new "Includes" facility, which was released in Tasks X.Y.Z.
+These searches are for experimenting with, and understanding, the new "Includes" facility, which was released in Tasks 7.20.0.
 
 presets values can be defined in the Tasks settings.
 

resources/sample_vaults/Tasks-Demo/Manual Testing/Invalid dates with Sorting and Grouping.md

@@ -45,7 +45,7 @@ hide task count
 
 ### Sort by due - built-in
 
-The invalid task is sorted before the dated ones, since Tasks X.Y.Z.
+The invalid task is sorted before the dated ones, since Tasks 6.0.0.
 
 ==FIXED==: [Bug report](https://github.com/obsidian-tasks-group/obsidian-tasks/issues/2589): **`sort by due` and similar should put tasks with invalid dates before the tasks with valid dates.**