Fix typo and add inline doc

Author: Kapil Borle

src/PowerShellEditorServices/Language/AstOperations.cs

@@ -211,7 +211,7 @@ static public IEnumerable<SymbolReference> FindSymbolsInDocument(Ast scriptAst,
             {
                 if (IsPowerShellDataFileAst(scriptAst))
                 {
-                    var findHashtableSymbolsVisitor = new FindHashtabeSymbolsVisitor();
+                    var findHashtableSymbolsVisitor = new FindHashtableSymbolsVisitor();
                     scriptAst.Visit(findHashtableSymbolsVisitor);
                     symbolReferences = findHashtableSymbolsVisitor.SymbolReferences;
                 }

src/PowerShellEditorServices/Language/FindSymbolsVisitor.cs

@@ -90,15 +90,27 @@ private bool IsAssignedAtScriptScope(VariableExpressionAst variableExpressionAst
         }
     }
 
-    internal class FindHashtabeSymbolsVisitor : AstVisitor
+    /// <summary>
+    /// Visitor to find all the keys in Hashtable AST
+    /// </summary>
+    internal class FindHashtableSymbolsVisitor : AstVisitor
     {
+        /// <summary>
+        /// List of symbols (keys) found in the hashtable
+        /// </summary>
         public List<SymbolReference> SymbolReferences { get; private set; }
 
-        public FindHashtabeSymbolsVisitor()
+        /// <summary>
+        /// Initializes a new instance of FindHashtableSymbolsVisitor class
+        /// </summary>
+        public FindHashtableSymbolsVisitor()
         {
             SymbolReferences = new List<SymbolReference>();
         }
 
+        /// <summary>
+        /// Adds keys in the input hashtable to the symbol reference
+        /// </summary>
         public override AstVisitAction VisitHashtable(HashtableAst hashtableAst)
         {
             if (hashtableAst.KeyValuePairs == null)