Update languages help

Recommend using a matrix build

Author: henrymercer

init/action.yml

@@ -8,7 +8,13 @@ inputs:
     # If not specified the Action will check in several places until it finds the CodeQL tools.
   languages:
     description: |
-      A comma-separated value of the languages to be analysed e.g. python,javascript
+      A comma-separated list of CodeQL languages to analyze.
+
+      Due to the performance benefit of parallelizing builds, we recommend specifying languages to
+      analyze using a matrix and providing `${{ matrix.language }}` as this input.
+
+      For more information, see
+      https://docs.github.com/en/code-security/code-scanning/creating-an-advanced-setup-for-code-scanning/customizing-your-advanced-setup-for-code-scanning#changing-the-languages-that-are-analyzed.
     required: false
   build-mode:
     description: >-