Small doc improvements.

Author: rocky

mathics/builtin/combinatorial.py

@@ -276,7 +276,7 @@ class StirlingS1(Builtin):
     """
     <dl>
       <dt>'StirlingS1[$n$, $m$]'
-      <dd>gives the Stirling number of the first kind S_n^m.
+      <dd>gives the Stirling number of the first kind $𝒮_n^m$.
     </dl>
 
     Integer mathematical function, suitable for both symbolic and numerical manipulation.
@@ -300,8 +300,8 @@ def apply(self, n, m, evaluation):
 class StirlingS2(Builtin):
     """
     <dl>
-      <dt>'StirlingS2[$n, $m$]'
-      <dd>gives the Stirling number of the second kind S_n^m.
+      <dt>'StirlingS2[$n$, $m$]'
+      <dd>gives the Stirling number of the second kind 𝒮_n^m.
     </dl>
 
     returns the number of ways of partitioning a set of $n$ elements into $m$ non‐empty subsets.

mathics/builtin/structure.py

@@ -530,6 +530,10 @@ class MapAt(Builtin):
     <dl>
       <dt>'MapAt[$f$, $expr$, $n$]'
       <dd>applies $f$ to the element at position $n$ in $expr$. If $n$ is negative, the position is counted from the end.
+      <dt>'MapAt[f, $exp$r, {$i$, $j$ ...}]'
+      <dd>applies $f$ to the part of $expr$ at position {$i$, $j$, ...}.
+      <dt>'MapAt[$f$,$pos$]'
+      <dd>represents an operator form of MapAt that can be applied to an expression.
     </dl>
 
     Map $f$ onto the part at position 2: