Adds a docstring with some horrendous html for better documentation o…

…n simsearch api endpoint, plus constraints

backend/src/monarch_py/api/semsim.py

@@ -1,6 +1,6 @@
 from typing import List
 
-from fastapi import APIRouter
+from fastapi import APIRouter, Query
 from monarch_py.api.config import oak
 from monarch_py.implementations.oak.oak_implementation import SemsimSearchCategory
 
@@ -56,10 +56,27 @@ def _post_compare(
 
 @router.get("/search")
 def _search(
-    subjects: str = "",
-    target_group: SemsimSearchCategory = None,
-    limit: int = 10,
+    subjects: str = Query(...),
+    target_group: SemsimSearchCategory = Query(...),
+    limit: int = Query(default=10, ge=1, le=500)
 ):
+    """
+    Search for genes or diseases by phenotype similarity<br>
+
+    Args:<br>
+        subjects (str, optional): A comma separated list of phenotypes, genes or diseases for comparison.<br>
+        Examples:
+            <ul>
+                <li>MONDO:0019391,</li>
+                <li>MP:0010771,MP:0002169,MP:0005391,MP:0005389,MP:0005367</li>
+                <li>HGNC:10848,HGNC:1101</li>
+            </ul>
+        <br>
+        target_group (SemsimSearchCategory, optional): The target group to search for, diseases, or genes
+            from a specific taxon<br>
+        limit: The maximum number of results to return (default 10, maximum of 500) <br>
+
+    """
     # TODO: subjects as an argument to this api method is consistent with compare,
     #       but obviously bizarre to have objects=subjects in the translation to oaklib
     return oak().search(objects=subjects.split(","), target_groups=[target_group], limit=limit)