Fix typos (#25)

Author: vil02

Diff for: doc/data_structures/sorted_set/sorted_set.md

@@ -4,7 +4,7 @@
 
 All operations operate on *values* rather than *references*.
 
-Contrary to popular textbooks, operations don't return references to interally used data structures (such as tree nodes).
+Contrary to popular textbooks, operations don't return references to internally used data structures (such as tree nodes).
 
 This makes some sequences of operations slower.
 For example if you first `find` a key and then upsert the same key using `insert`;

Diff for: src/data_structures/sorted_set/binary_search_tree.lua

@@ -99,7 +99,7 @@ function bst:succ(key)
 	return node and node.key
 end
 
--- Analogeous to `succ`
+-- Analogous to `succ`
 local function pred_node(self, key)
 	local less_than = self.less_than
 	local function pred(node)

Diff for: src/data_structures/sorted_set/btree.lua

@@ -268,7 +268,7 @@ function btree:range_ascending(min_key, max_key)
 	end)
 end
 
--- Analogeous to `range_ascending`
+-- Analogous to `range_ascending`
 function btree:range_descending(min_key, max_key)
 	if min_key == nil and max_key == nil then
 		return self:descending()