Add FAQ to docs page.

Author: csyonghe

docs/index.md

@@ -18,6 +18,20 @@ The formal specification of the Slang programming language. Work in progress.
 List of Slang Features with their stableness/matureness.
 
 
+## Frequently Asked Questions
+
+#### Does Slang use LLVM?
+
+No. The Slang compiler itself is not built on the LLVM tech stack, and does not depend on LLVM.
+If you are using Slang to generate textual or SPIRV code, no LLVM binaries are required. If you are using Slang to produce standalone executables or dynamically linked
+libraries, then a prebuilt LLVM wrapper library called `slang-llvm` is required.
+
+#### What's the distribution size of Slang?
+
+The Slang compiler binary is around 5-10 MB depending on build configuration and target architecture.
+
+
+
 ## Articles
 
 #### [The Commandline Tool Reference](https://github.com/shader-slang/slang/blob/master/docs/command-line-slangc-reference.md)