Prevent markdownlint errors

Some descriptions cause markdownlint errors when exposed in our docs.
To prepare for this, we make the following changes:

- Use Prometheus instead of prometheus
- Escape example URLs

app/graphql/mutations/alert_management/prometheus_integration/create.rb

@@ -18,7 +18,7 @@ module Mutations
 
         argument :api_url, GraphQL::STRING_TYPE,
                  required: true,
-                 description: 'Endpoint at which prometheus can be queried.'
+                 description: 'Endpoint at which Prometheus can be queried.'
 
         def resolve(args)
           project = authorized_find!(args[:project_path])

app/graphql/mutations/alert_management/prometheus_integration/update.rb

@@ -16,7 +16,7 @@ module Mutations
 
         argument :api_url, GraphQL::STRING_TYPE,
                  required: false,
-                 description: "Endpoint at which prometheus can be queried."
+                 description: "Endpoint at which Prometheus can be queried."
 
         def resolve(args)
           integration = authorized_find!(id: args[:id])

app/graphql/resolvers/metrics/dashboard_resolver.rb

@@ -8,15 +8,16 @@ module Resolvers
 
       argument :path, GraphQL::STRING_TYPE,
                required: true,
-               description: "Path to a file which defines metrics dashboard " \
-                            "eg: 'config/prometheus/common_metrics.yml'."
+               description: <<~MD
+                 Path to a file which defines metrics dashboard eg: `"config/prometheus/common_metrics.yml"`.
+               MD
 
       alias_method :environment, :object
 
-      def resolve(**args)
+      def resolve(path:)
         return unless environment
 
-        ::PerformanceMonitoring::PrometheusDashboard.find_for(**args, **service_params)
+        ::PerformanceMonitoring::PrometheusDashboard.find_for(path: path, **service_params)
       end
 
       private

app/graphql/resolvers/milestones_resolver.rb

@@ -7,7 +7,7 @@ module Resolvers
 
     argument :ids, [GraphQL::ID_TYPE],
              required: false,
-             description: 'Array of global milestone IDs, e.g., "gid://gitlab/Milestone/1".'
+             description: 'Array of global milestone IDs, e.g., `"gid://gitlab/Milestone/1"`.'
 
     argument :state, Types::MilestoneStateEnum,
              required: false,