docs: enhance README and CONTRIBUTING with improved onboarding

.agent_instructions/documentation.md

@@ -68,12 +68,12 @@ Use dash-case (aka kebab-case) for the [Title] of the ADR.
 - The license should be at the very top of each source file, before any using statements or code.
 - We use the MIT license.
 - You should add your name and the year, if it is a new file.
-- You should put the license comment in a `# region License` block
+- You should put the license comment in a `#region Licence` block (note: British spelling, no space)
 - An LLM should use the name and year of the contributor instructing the LLM
 - As an example
 
 ```csharp
-#region License
+#region Licence
 
 /* The MIT License (MIT)
 Copyright © [Year] [Your Name] [Your Contact Email]
@@ -96,5 +96,5 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE. */
 
-# endregion
+#endregion
 ```

.github/copilot-instructions.md

@@ -3,7 +3,7 @@ applyTo: '**'
 ---
 
 ## How to Use This File
-This file contains instructions for GitHub Copilot to help it understand the context and requirements of the project. It is not intended to be modified by contributors. Human contributors should follow the guidelines in the [CONTRIBUTING.md](CONTRIBUTING.md) file. These guidelines derive from that document.
+This file contains instructions for GitHub Copilot to help it understand the context and requirements of the project. It is not intended to be modified by contributors. Human contributors should follow the guidelines in the [CONTRIBUTING.md](../CONTRIBUTING.md) file. These guidelines derive from that document.
 
 ## Detailed Instructions
 For comprehensive guidance on working with this codebase, Copilot should read the following files as needed: