docs: add examples for regex operators (closes #6919)

GITHUB_PR_NUMBER: 7691
GITHUB_PR_URL: https://github.com/hasura/graphql-engine/pull/7691

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2618
Co-authored-by: Rafael Baldasso Audibert <32079912+rafaeelaudibert@users.noreply.github.com>
Co-authored-by: Rikin Kachhia <54616969+rikinsk@users.noreply.github.com>
GitOrigin-RevId: eeec4eba087c10d7008092a1f70acc82e73c4fcc

docs/graphql/core/databases/postgres/queries/query-filters.rst

@@ -472,8 +472,8 @@ Fetch a list of those authors whose names are NOT part of a list:
       }
     }
 
-Text search or pattern matching operators (_like, _similar, etc.)
+Text search or pattern matching operators (_like, _similar, _regex, etc.)
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 The ``_like``, ``_nlike``, ``_ilike``, ``_nilike``, ``_similar``, ``_nsimilar``, ``_regex``, ``_nregex``, ``_iregex``, ``_niregex`` operators are used for
 pattern matching on string/text fields.
@@ -512,6 +512,8 @@ Fetch a list of articles whose titles contain the word “amet”:
             "title": "sit amet"
           }
         ]
+      }
+    }
 
 .. note::
 
@@ -561,6 +563,49 @@ Fetch a list of authors whose names begin with A or C:
 
   ``_similar`` is case-sensitive
 
+**Example: _regex**
+
+Fetch a list of articles whose titles match the regex “[ae]met”:
+
+.. graphiql::
+  :view_only:
+  :query:
+    query {
+      articles(
+        where: {title: {_regex: "[ae]met"}}
+      ) {
+        id
+        title
+      }
+    }
+  :response:
+    {
+      "data": {
+        "articles": [
+          {
+            "id": 1,
+            "title": "sit amet"
+          },
+          {
+            "id": 3,
+            "title": "cremet justo morbi"
+          },
+          {
+            "id": 9,
+            "title": "sit ametist"
+          }
+        ]
+      }
+    }  
+
+.. note::
+
+  ``_regex`` is case-sensitive. Use ``_iregex`` for case-insensitive search.
+
+.. note::
+
+  ``regex`` operators are supported in in ``v2.0.0`` and above
+
 JSONB operators (_contains, _has_key, etc.)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^