Update README.md

Co-authored-by: Owen Voorhees <owenvoorhees@gmail.com>

Author: cltnschlosser

README.md

@@ -107,7 +107,7 @@ After the toolchain is installed, Xcode needs to be told to use it. This can mea
 
 Building with the toolchain is easy, set the toolchain in Xcode: Menu Bar > Xcode > Toolchains > select your toolchain
 
-Running the driver requires setting the TOOLCHAINS environment variable. This tells xcrun which toolchain to use, on darwin xcrun is used to find tools. This variable is the name of the toolchain and not the path (ex: `Swift Development Snapshot`). Important note: xcrun is lower priority than SWIFT_EXEC_*_EXEC family of environment variables, tools directory, and for anything in the same directory as the driver (This includes a driver installed in a toolchain). Even though TOOLCHAINS is not highest priority it's a convenient one change for running the xctest suite against a custom toolchain.
+Running the driver requires setting the TOOLCHAINS environment variable. This tells xcrun which toolchain to use (on darwin xcrun is used to find tools). This variable is the name of the toolchain and not the path (ex: `Swift Development Snapshot`). Important note: xcrun lookup is lower priority than the SWIFT_EXEC_*_EXEC family of environment variables, the tools directory, and any tools in the same directory as the driver (This includes a driver installed in a toolchain). Even though TOOLCHAINS is not highest priority it's a convenient way to run the xctest suite using a custom toolchain.
 
 #### Preparing a Linux docker for debug