add some copy-paste goodness

Author: tshepang

src/tests/running.md

@@ -363,20 +363,20 @@ codegen-backends = ["llvm", "gcc"]
 Then you need to install libgccjit 12. For example with `apt`:
 
 ```text
-$ apt install libgccjit-12-dev
+apt install libgccjit-12-dev
 ```
 
 Now you can run the following command:
 
 ```text
-$ ./x test compiler/rustc_codegen_gcc/
+./x test compiler/rustc_codegen_gcc/
 ```
 
 If it cannot find the `.so` library (if you installed it with `apt` for example), you
 need to pass the library file path with `LIBRARY_PATH`:
 
 ```text
-$ LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/12/ ./x test compiler/rustc_codegen_gcc/
+LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/12/ ./x test compiler/rustc_codegen_gcc/
 ```
 
 If you encounter bugs or problems, don't hesitate to open issues on the