[SPARKR][BUILD] ignore cran-check.out under R folder

## What changes were proposed in this pull request?

(Please fill in changes proposed in this fix)
R add cran check which will generate the cran-check.out. This file should be ignored in git.

## How was this patch tested?

(Please explain how this patch was tested. E.g. unit tests, integration tests, manual tests)
Manual test it. Run clean test and git status to make sure the file is not included in git.

Author: wm624@hotmail.com <wm624@hotmail.com>

Closes #14774 from wangmiao1981/ignore.

.gitignore

@@ -23,6 +23,7 @@
 /lib/
 R-unit-tests.log
 R/unit-tests.out
+R/cran-check.out
 build/*.jar
 build/apache-maven*
 build/scala*