gitlab.sh: Use stderr to print errors

To follow good practices print errors to stderr, this is special important
on shell scripts since stdout is piped. While doing that fix typos in error
messages.

Signed-off-by: Walter Lozano <walter.lozano@collabora.com>

release-scripts/gitlab.sh

@@ -6,7 +6,7 @@ api(){
         . ~/.gitlab-apertis-org-token
     fi
 
-    [ -z "$CI_SERVER_HOST" ] && ( echo "No server host specified, use CI_SERVER_HOST env var to specify tit" >&2 ; exit 1 )
+    [ -z "$CI_SERVER_HOST" ] && (echo "No server host specified, use CI_SERVER_HOST env var to specify it" >&2 ; exit 1 )
 
     api_base_url=https://gitlab.apertis.org/api/v4
     api_endpoint=$1
@@ -117,9 +117,9 @@ trigger-pipeline(){
     set -e
 
     usage () {
-        echo "Usage: $0 <package> <pipeline>"
-        echo ""
-        echo "Example: $0 libfoo debian/sid"
+        echo "Usage: trigger-pipeline <package> <pipeline>" >&2
+        echo "" >&2
+        echo "Example: trigger-pipeline libfoo debian/sid" >&2
     }
 
     if [ "$#" -ne 2 ]; then