doc: nitpick

Author: tony-go

doc/contributing/diagnostic-tooling-support-tiers.md

@@ -9,7 +9,7 @@ The Node.js project has assessed the tools and the APIs which support those
 tools. Each of the tools and APIs has been put into one of
 the following tiers.
 
-* Tier 1 - Must always be working(CI tests passing) for all
+* Tier 1 - Must always be working (CI tests passing) for all
   Current and LTS Node.js releases. A release will not be shipped if the test
   suite for the tool/API is not green. To be considered for inclusion
   in this tier it must have a good test suite and that test suite and a job
@@ -29,7 +29,7 @@ the following tiers.
     its dependencies; and
   * The tool must be open source.
 
-* Tier 2 - Must be working(CI tests passing) for all
+* Tier 2 - Must be working (CI tests passing) for all
   LTS releases. An LTS release will not be shipped if the test
   suite for the tool/API is not green. To be considered for inclusion
   in this tier it must have a good test suite and that test suite and a job