Update the error thrown by Bazel

Hello,

The error message thrown by Bazel in step 4 should be updated.
The label of the toolchain specified in step 3 is **//toolchain:asmjs_toolchain** and not **//toolchain:asmjs_toolchain_config**.
Therefore the error message should be
```
    Rule '//toolchain:asmjs_toolchain' does not exist
```
Kind regards,
George

Closes #10509.

PiperOrigin-RevId: 295594362
diff --git a/site/docs/tutorial/cc-toolchain-config.md b/site/docs/tutorial/cc-toolchain-config.md
index d1ab3af..771e0a6 100644
--- a/site/docs/tutorial/cc-toolchain-config.md
+++ b/site/docs/tutorial/cc-toolchain-config.md
@@ -170,7 +170,7 @@
     Rule '//toolchain:asmjs-toolchain' does not exist
     ```
 
-    Let's add a ":asmjs-toolchain-config" target to the `toolchain/BUILD` file:
+    Let's add a ":asmjs_toolchain_config" target to the `toolchain/BUILD` file:
 
     ```
     filegroup(name = "asmjs_toolchain_config")