.Net: docs(dotnet): supply maxTokens to avoid response truncation (microsoft#2249)

### Motivation and Context

  1. Why is this change required?

When working through the examples in the dotnet/README.md file, I
noticed that [OpenAI sets the max_tokens to
16](https://platform.openai.com/docs/api-reference/completions/create),
which is far too low for these examples and led to truncated output and
failing prompt chaining examples.

  3. What problem does it solve?

This makes the README.md examples work again.

  5. What scenario does it contribute to?

Onboarding/experimentation.

  8. If it fixes an open issue, please link to the issue here.

- [x] The code builds clean without any errors or warnings
- [x] 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
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

Co-authored-by: Shawn Callegari <[email protected]>

Author: 2 people

dotnet/README.md

@@ -41,7 +41,7 @@ var prompt = @"{{$input}}
 
 One line TLDR with the fewest words.";
 
-var summarize = kernel.CreateSemanticFunction(prompt);
+var summarize = kernel.CreateSemanticFunction(prompt, maxTokens: 100);
 
 string text1 = @"
 1st Law of Thermodynamics - Energy cannot be created or destroyed.
@@ -80,8 +80,8 @@ string summarizePrompt = @"{{$input}}
 
 Give me a TLDR with the fewest words.";
 
-var translator = kernel.CreateSemanticFunction(translationPrompt);
-var summarize = kernel.CreateSemanticFunction(summarizePrompt);
+var translator = kernel.CreateSemanticFunction(translationPrompt, maxTokens: 200);
+var summarize = kernel.CreateSemanticFunction(summarizePrompt, maxTokens: 100);
 
 string inputText = @"
 1st Law of Thermodynamics - Energy cannot be created or destroyed.