ci examples: clarify code coverage comments

Author: jrchamp

.travis.dist.yml

@@ -34,9 +34,10 @@ env:
 before_install:
   - if [[ ${TRAVIS_PHP_VERSION:0:1} -gt 7 ]]; then pecl install xmlrpc-beta; fi
   - echo 'max_input_vars=5000' >> ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini
-  # Don't disable xdebug if you want to get it used for code coverage.
+  # We remove xdebug by default for performance, because we're not checking code coverage.
+  # If you want to use xdebug for code coverage, remove this line.
   - phpenv config-rm xdebug.ini
-  # Alternative (for Moodle 3.10 and up) is to use pcov. It can be installed using:
+  # To use pcov for code coverage on Moodle 3.10 and up, install it using:
   # - pecl install pcov
   - cd ../..
   - composer create-project -n --no-dev --prefer-dist moodlehq/moodle-plugin-ci ci ^3

docs/GHAFileExplained.md

@@ -95,7 +95,8 @@ jobs:
           php-version: ${{ matrix.php }}
           extensions: ${{ matrix.extensions }}
           ini-values: max_input_vars=5000
-          # none to use phpdbg fallback. Specify pcov (Moodle 3.10 and up) or xdebug to use them instead.
+          # If you are not using code coverage, keep "none". Otherwise, use "pcov" (Moodle 3.10 and up) or "xdebug".
+          # If you try to use code coverage with "none", it will fallback to phpdbg (which has known problems).
           coverage: none
 
       # Install this project into a directory called "ci", updating PATH and

docs/TravisFileExplained.md

@@ -89,8 +89,11 @@ before_install:
 - if [[ ${TRAVIS_PHP_VERSION:0:1} -gt 7 ]]; then pecl install xmlrpc-beta; fi
 # Setup a good default max_input_vars value for all runs.
 - echo 'max_input_vars=5000' >> ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini
-# This disables XDebug which should speed up the build.
+# We remove xdebug by default for performance, because we're not checking code coverage.
+# If you want to use xdebug for code coverage, remove this line.
   - phpenv config-rm xdebug.ini
+# To use pcov for code coverage on Moodle 3.10 and up, install it using:
+# - pecl install pcov
 # Currently we are inside of the clone of your repository.  We move up two
 # directories to build the project.
   - cd ../..

gha.dist.yml

@@ -46,7 +46,8 @@ jobs:
           php-version: ${{ matrix.php }}
           extensions: ${{ matrix.extensions }}
           ini-values: max_input_vars=5000
-          # none to use phpdbg fallback. Specify pcov (Moodle 3.10 and up) or xdebug to use them instead.
+          # If you are not using code coverage, keep "none". Otherwise, use "pcov" (Moodle 3.10 and up) or "xdebug".
+          # If you try to use code coverage with "none", it will fallback to phpdbg (which has known problems).
           coverage: none
 
       - name: Initialise moodle-plugin-ci