fix: non-substantive typos (#434)

Co-authored-by: Viktor Szépe <viktor@szepe.net>
Co-authored-by: Edward Z. Yang <ezyang@mit.edu>

library/HTMLPurifier/Strategy/FixNesting.php

@@ -20,7 +20,7 @@
  * The second objective is to ensure that explicitly excluded elements of
  * an element do not appear in its children.  Code that accomplishes this
  * task is pervasive through the strategy, though the two are distinct tasks
- * and could, theoretically, be seperated (although it's not recommended).
+ * and could, theoretically, be separated (although it's not recommended).
  *
  * @note Whether or not unrecognized children are silently dropped or
  *       translated into text depends on the child definitions.

library/HTMLPurifier/Strategy/MakeWellFormed.php

@@ -641,7 +641,7 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
 //    Needless to say, we need to UN-skip the token so it gets
 //    reprocessed.
 //
-//  - Suppose that you successfuly process a token, replace it with
+//  - Suppose that you successfully process a token, replace it with
 //    one with your skip mark, but now another injector wants to
 //    process the skipped token with another token.  Should you continue
 //    to skip that new token, or reprocess it?  If you reprocess,