chore(docs): updating data catalog refresh process

docs/tables/mpe_datacatalog_libs.md

@@ -25,5 +25,22 @@ To ignore additional librefs, or to trigger a scan, see the Refresh Data Catalog
  - `SCHEMAS char(500)`: The library schema (DB engines)
  - `LIBID char(17)`: The Library Id (from metadata if SAS 9)
 
+## Refresh Process
+
+The table is refreshed by the `mpe_refreshlibs` macro, which runs:
+
+- When a user clicks the refresh icon next to a library in the VIEW menu (via the `refreshlibinfo` service)
+- For ALL libraries when an administrator clicks REFRESH on the System page (via the `refreshlibs` service)
+
+The refresh is driven primarily from `dictionary.libnames`, augmented with library name / id from metadata (SAS 9 only). Noteworthy behaviours:
+
+- The `V9` engine is normalised to `BASE`
+- Concatenated libraries produce multiple quoted entries in `PATHS`, with one comma-separated `PERMS` / `OWNERS` value per path
+- `SCHEMAS` is populated for database engines
+- On SAS 9 (metadata) deployments, invalid libraries are validated by attempting a META libname assignment and skipped on failure. If your environment has invalid libraries that cause exception errors, set the `DC_VIEWLIB_CHECK` config variable to `NO` in Data Controller Settings
+- The following librefs are always excluded: `SASWORK`, `WORK`, `SASUSER`, `CASUSER`, `TEMP`, `STPSAMP`, `MAPSGFK`. Additional librefs can be ignored via `DC_IGNORELIBS` (see [Refreshing the Data Catalog](/dcu-datacatalog/#refreshing-the-data-catalog))
+
+The load is TXTEMPORAL on the `LIBREF` key, so records are closed out (not deleted) when a library disappears.
+