Update README to remove reference to submodules (#18427)

After #15855, this repo no longer uses submodules. Removing instruction
about needing to initialize them.

README.md

@@ -362,15 +362,6 @@ If you would like to ask a question that you feel doesn't warrant an issue
 
 ## Building the Code
 
-This repository uses [git
-submodules](https://git-scm.com/book/en/v2/Git-Tools-Submodules) for some of its
-dependencies. To make sure submodules are restored or updated, be sure to run
-the following prior to building:
-
-```shell
-git submodule update --init --recursive
-```
-
 OpenConsole.sln may be built from within Visual Studio or from the command-line
 using a set of convenience scripts & tools in the **/tools** directory: