Update param description to make it more user-friendly

Update some outdate parameter descriptions to make it more clear to
users on how to set the params.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I3cc83ec51a30b51c0b2eb04fc4725f243b698ad8
diff --git a/tf-m-code-coverage.yaml b/tf-m-code-coverage.yaml
index dd46aa2..3683fc1 100644
--- a/tf-m-code-coverage.yaml
+++ b/tf-m-code-coverage.yaml
@@ -28,8 +28,6 @@
       - string:
           name: 'CODE_REPO'
           default: 'https://git.trustedfirmware.org/TF-M/trusted-firmware-m'
-          description: |
-            Change to https://review.trustedfirmware.org/TF-M/trusted-firmware-m use when triggering with unmerged Gerrit changes.
       - string:
           name: 'CI_SCRIPTS_REPO'
           default: 'https://git.trustedfirmware.org/ci/tf-m-ci-scripts'
@@ -45,22 +43,27 @@
           name: 'GERRIT_BRANCH'
           default: 'master'
           description: |
-            For use when triggering with unmerged Gerrit changes.
+            TF-M branch.
       - string:
           name: 'GERRIT_HOST'
           description: |
-            For use when triggering with unmerged Gerrit changes.
+            No need to change.
       - string:
           name: 'GERRIT_CHANGE_NUMBER'
           description: |
-            For use when triggering with unmerged Gerrit changes.
+            No need to change.
       - string:
           name: 'GERRIT_PATCHSET_REVISION'
           description: |
-            For use when triggering with unmerged Gerrit changes.
+            No need to change.
       - string:
           name: 'MBEDTLS_VERSION'
           default: 'mbedtls-3.3.0'
+          description: |
+            Specify which MBEDTLS version to use
+            refs/heads/<branch_name> : Pick up latest HEAD on branch
+            TAG_NAME                 : Pick up a tagged version
+            full commit hash         : Pick up a specific commit
       - string:
           name: 'MBEDTLS_URL'
           default: 'https://git.trustedfirmware.org/mirror/mbed-tls.git'
@@ -70,6 +73,11 @@
       - string:
           name: 'QCBOR_VERSION'
           default: '92d3f89030baff4af7be8396c563e6c8ef263622'
+          description: |
+            Specify which QCBOR version to use
+            refs/heads/<branch_name> : Pick up latest HEAD on branch
+            TAG_NAME                 : Pick up a tagged version
+            full commit hash         : Pick up a specific commit
       - string:
           name: 'LAVA_URL'
           default: 'https://tf.validation.linaro.org'
@@ -94,8 +102,9 @@
           default: 'v1.9.0'
           description: |
             Specify which MCUboot version to use
-            refs/heads/master    : Pick up latest master
-            refs/tags/<TAG_NAME> : Pick up a tagged version
+            refs/heads/<branch_name> : Pick up latest HEAD on branch
+            TAG_NAME                 : Pick up a tagged version
+            full commit hash         : Pick up a specific commit
       - string:
           name: 'MCUBOOT_URL'
           default: 'https://git.trustedfirmware.org/mirror/mcuboot.git'
@@ -105,12 +114,22 @@
       - string:
           name: 'TFM_TESTS_REFSPEC'
           default: 'refs/heads/master'
+          description: |
+            Specify which tf-m-tests version to use
+            refs/heads/<branch_name> : Pick up latest HEAD on branch
+            TAG_NAME                 : Pick up a tagged version
+            full commit hash         : Pick up a specific commit
       - string:
           name: 'PSA_ARCH_TESTS_URL'
           default: 'https://git.trustedfirmware.org/mirror/psa-arch-tests.git'
       - string:
           name: 'PSA_ARCH_TESTS_VERSION'
           default: 'cf8bd7191219df9bdef387abcd750f0709283f98'
+          description: |
+            Specify which psa-arch-tests version to use
+            refs/heads/<branch_name> : Pick up latest HEAD on branch
+            TAG_NAME                 : Pick up a tagged version
+            full commit hash         : Pick up a specific commit
       - string:
           name: 'EMAIL_NOTIFICATION'
           default: 'xinyu.zhang@arm.com, paul.sokolovsky@linaro.org'