Clarify tsBuildInfoFile isn't a folder (#2303)

Author: jablko

packages/tsconfig-reference/copy/en/options/tsBuildInfoFile.md

@@ -1,10 +1,10 @@
 ---
 display: "TS Build Info File"
-oneline: "Specify the folder for .tsbuildinfo incremental compilation files."
+oneline: "The file to store `.tsbuildinfo` incremental build information in."
 ---
 
 This setting lets you specify a file for storing incremental compilation information as a part of composite projects which enables faster
 building of larger TypeScript codebases. You can read more about composite projects [in the handbook](/docs/handbook/project-references.html).
 
-This option offers a way to configure the place where TypeScript keeps track of the files it stores on the disk to
-indicate a project's build state — by default, they are in the same folder as your emitted JavaScript.
+By default it is in the same folder as your emitted JavaScript and has a `.tsbuildinfo` file extension.
+The default file name is based on the `outFile` option or your tsconfig file name.