fix(integration-docs): point CustomAlert at renamed standard-alert.mdx (#104)

doc-map.mjs still referenced 'standard alert.mdx' (space), but the file was
renamed to 'standard-alert.mdx' (hyphen). The build throws on the first
missing source, breaking the OSS compatibility-bundle pipeline on any push
that touches on-call/integration/**. Local build now succeeds (77 keys).

Author: ysyneu

integration-docs/src/doc-map.mjs

@@ -2,7 +2,7 @@ const alertBase = 'on-call/integration/alert-integration/alert-sources';
 const integrationBase = 'on-call/integration';
 
 export const docMap = {
-  CustomAlert: `${alertBase}/standard alert.mdx`,
+  CustomAlert: `${alertBase}/standard-alert.mdx`,
   Email: `${alertBase}/email.mdx`,
   N9e: `${alertBase}/flashcat.mdx`,
   Prometheus: `${alertBase}/prometheus.mdx`,