Consistent capitalization of language name (#7)

Capitalization helps distinguish the language name from the common noun "slang". The home page always capitalizes the S, fix the few remaining instances without in the `Getting Started` page.

Author: mmoult

docs/getting-started.md

@@ -2,7 +2,7 @@
 
 ## Try Slang
 
-Try slang locally in your browser without downloading or installing anything with [Slang-Playground](/slang-playground).
+Try Slang locally in your browser without downloading or installing anything with [Slang-Playground](/slang-playground).
 
 ## Download Prebuilt Release
 
@@ -24,8 +24,8 @@ Instructions for building Slang from source code are maintained as part of the s
 
 ## Your First Slang Shader
 
-Follow [this tutorial](/docs/first-slang-shader) on how to write your first slang shader and compile it for execution with the Vulkan API.
+Follow [this tutorial](/docs/first-slang-shader) on how to write your first Slang shader and compile it for execution with the Vulkan API.
 
 ## The User-Guide
 
-Check out the [Slang User's Guide](https://shader-slang.com/slang/user-guide/index.html) to learn more about the language features, and [Slang Standard Library Reference](https://shader-slang.com/stdlib-reference) for detailed documentation on Slang's builtin types and functions available for use in your shader code.
+Check out the [Slang User's Guide](https://shader-slang.com/slang/user-guide/index.html) to learn more about the language features, and [Slang Standard Library Reference](https://shader-slang.com/stdlib-reference) for detailed documentation on Slang's builtin types and functions available for use in your shader code.