Do not exclude entire README from spell checking (#10122)

### Motivation and Context

Closes #9898

### Description

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These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

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- [ ] The code builds clean without any errors or warnings
- [ ] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [ ] All unit tests pass, and I have added new tests where possible
- [ ] I didn't break anyone 😄

.github/_typos.toml

@@ -23,8 +23,7 @@ extend-exclude = [
     "PopulationByCountry.csv",
     "PopulationByAdmin1.csv",
     "WomensSuffrage.txt",
-    "SK-dotnet.sln.DotSettings",
-    "dotnet/samples/Concepts/Resources/Plugins/CopilotAgentPlugins/README.md"
+    "SK-dotnet.sln.DotSettings"
 ]
 
 [default.extend-words]
@@ -39,6 +38,7 @@ arange = "arange"         # Method in Python numpy package
 prompty = "prompty"       # prompty is a format name.
 ist = "ist"               # German language
 dall = "dall"             # OpenAI model name
+pn = "pn"                 # Kiota parameter
 
 [default.extend-identifiers]
 ags = "ags" # Azure Graph Service