Fix link to wasm sources (#67)

Author: chicoxyzzy

README.md

@@ -232,7 +232,7 @@ API
 WebAssembly support
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-[WebAssembly](http://webassembly.org) supports 64-bit integer arithmetic out of the box, hence a [tiny WebAssembly module](./src/wasm.wast) is used to compute operations like multiplication, division and remainder more efficiently (slow operations like division are around twice as fast), falling back to floating point based computations in JavaScript where WebAssembly is not yet supported, e.g., in older versions of node.
+[WebAssembly](http://webassembly.org) supports 64-bit integer arithmetic out of the box, hence a [tiny WebAssembly module](./src/wasm.wat) is used to compute operations like multiplication, division and remainder more efficiently (slow operations like division are around twice as fast), falling back to floating point based computations in JavaScript where WebAssembly is not yet supported, e.g., in older versions of node.
 
 Building
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