Fix test tag argument typo

The argument is --test_tag_filters, not --test_tag_filter.

Also switch to ... instead of :*, as it doesn't require special shell
quoting to avoid * expansion.

PiperOrigin-RevId: 224949618
Change-Id: I45dd6acbaeae29f2cc0baa977b086b5c037c6a88

Author: prattmic

test/syscalls/README.md

@@ -39,21 +39,21 @@ tag:
 
 ```bash
 # Run all tests in native environment:
-$ bazel test --test_tag_filter=native //test/syscalls:*
+$ bazel test --test_tag_filters=native //test/syscalls/...
 
 # Run all tests in runsc with ptrace:
-$ bazel test --test_tag_filter=runsc_ptrace //test/syscalls:*
+$ bazel test --test_tag_filters=runsc_ptrace //test/syscalls/...
 
 # Run all tests in runsc with kvm:
-$ bazel test --test_tag_filter=runsc_kvm //test/syscalls:*
+$ bazel test --test_tag_filters=runsc_kvm //test/syscalls/...
 ```
 
 You can also run all the tests on every platform. (Warning, this may take a
 while to run.)
 
 ```bash
 # Run all tests on every platform:
-$ bazel test //test/syscalls:*
+$ bazel test //test/syscalls/...
 ```
 
 ## Writing new tests