Circulars - Add Documentation for the Circulars Archive Search Functi…

…onality (nasa-gcn#2503)

Resolves nasa-gcn#2501.

app/routes/docs.circulars.archive.mdx

@@ -13,6 +13,12 @@ Upon successful submission and distribution, a GCN Circular is assigned a number
   Go to GCN Circulars Archive
 </Link>
 
+## Searching the Archive
+
+You can search the Circulars Archive by keywords or phrases in the subject, body, and submitter fields. By default, results will be returned in reverse chronological order, but you can also choose to sort the results by relevance. You can navigate through the search results using pagination controls and specify the number of results to display per page. By default, 100 results are displayed per page.
+
+You can also filter search results by submission date. Select the dropdown button labeled "Filter by date". From there, you can either select from a number of predefined time ranges (e.g., "Last Hour", "Last Day", etc.) or specify a custom date range, which can either be set as a start date, an end date, or both. All search filters can be cleared by clicking the 'x' button in the search bar.
+
 ## Citing GCN Circulars
 
 The [SAO/NASA Astrophysics Data System (ADS)](https://ui.adsabs.harvard.edu) ingests and indexes all GCN Circulars. You can use ADS to get bibliographic records for GCN Circulars to cite them in a publication.