Fix meaning of emcc

Author: juntyr

src/doc/rustc/src/platform-support/wasm32-unknown-emscripten.md

@@ -40,12 +40,12 @@ If you are only targeting the web and need to access web APIs, the
 
 ## Requirements
 
-This target is cross-compiled. The Emscripten compiler toolchain (emsdk) must be
-installed to link WASM binaries with `emcc`. Please refer to
+This target is cross-compiled. The Emscripten compiler toolchain `emcc` must be
+installed to link WASM binaries for this target. Please refer to
 <https://emscripten.org/docs/getting_started/downloads.html> on how to get started
-with the emsdk.
+with and install `emcc`.
 
-You can also build the emsdk from source with:
+You can also build `emcc` from source with:
 
 ```sh
 git clone https://github.com/emscripten-core/emsdk.git --depth 1