Fix repeated typo in help strings.

src/db-up/azext_db_up/_help.py

@@ -10,7 +10,7 @@
     type: command
     short-summary: Set up an Azure Database for MySQL server and configurations.
     examples:
-        - name: Ensure that a Azure Database for MySQL server is up and running and configured for immediate use.
+        - name: Ensure that an Azure Database for MySQL server is up and running and configured for immediate use.
           text: az mysql up
         - name: To override default names, provide parameters indicating desired values/existing resources.
           text: az mysql up -g MyResourceGroup -s MyServer -d MyDatabase -u MyUsername -p MyPassword
@@ -20,7 +20,7 @@
     type: command
     short-summary: Set up an Azure Database for PostgreSQL server and configurations.
     examples:
-        - name: Ensure that a Azure Database for PostgreSQL server is up and running and configured for immediate use.
+        - name: Ensure that an Azure Database for PostgreSQL server is up and running and configured for immediate use.
           text: az postgres up
         - name: To override default names, provide parameters indicating desired values/existing resources.
           text: az postgres up -g MyResourceGroup -s MyServer -d MyDatabase -u MyUsername -p MyPassword
@@ -30,7 +30,7 @@
     type: command
     short-summary: Set up an Azure Database for SQL server and configurations.
     examples:
-        - name: Ensure that a Azure Database for SQL server is up and running and configured for immediate use.
+        - name: Ensure that an Azure Database for SQL server is up and running and configured for immediate use.
           text: az sql up
         - name: To override default names, provide parameters indicating desired values/existing resources.
           text: az sql up -g MyResourceGroup -s MyServer -d MyDatabase -u MyUsername -p MyPassword