fix casing of clr flag

Author: TylerMSFT

docs/cpp/transporting-exceptions-between-threads.md

@@ -73,7 +73,7 @@ Only the following combination of compiler options and programming statements ca
 
 - The **`/EHa`**, **`/EHs`**, and **`/EHsc`** compiler options and the **`catch`** statement can transport C++ exceptions.
 
-- The **`/CLR`** compiler option and the **`catch`** statement can transport C++ exceptions. The **`/clr`** compiler option implies specification of the **`/EHa`** option. The compiler doesn't support transporting managed exceptions. This is because managed exceptions, which are derived from the [System.Exception class](../standard-library/exception-class.md), are already objects that you can move between threads by using the facilities of the common language runtime.
+- The **`/clr`** compiler option and the **`catch`** statement can transport C++ exceptions. The **`/clr`** compiler option implies specification of the **`/EHa`** option. The compiler doesn't support transporting managed exceptions. This is because managed exceptions, which are derived from the [System.Exception class](../standard-library/exception-class.md), are already objects that you can move between threads by using the facilities of the common language runtime.
 
    > [!IMPORTANT]
    > We recommend that you specify the **`/EHsc`** compiler option and catch only C++ exceptions. You expose yourself to a security threat if you use the **`/EHa`** or **`/clr`** compiler option and a **`catch`** statement with an ellipsis *exception-declaration* (`catch(...)`). You probably intend to use the **`catch`** statement to capture a few specific exceptions. However, the `catch(...)` statement captures all C++ and SEH exceptions, including unexpected ones that should be fatal. If you ignore or mishandle an unexpected exception, malicious code can use that opportunity to undermine the security of your program.