Fix minor typos

[sredna]

[spaette]

https://github.com/madler/zlib/pull/673#issuecomment-1224913167

---

FWIW, this would make more sense to me.

  /*
     Compare two filenames (fileName1,fileName2).
-    If iCaseSenisivity = 1, comparision is case sensitivity (like strcmp)
-    If iCaseSenisivity = 2, comparision is not case sensitivity (like strcmpi
+    If iCaseSensitivity = 1, comparison is with case sensitivity (like strcmp)
+    If iCaseSensitivity = 2, comparison is without case sensitivity (like strcmpi
                                  or strcasecmp)
-    If iCaseSenisivity = 0, case sensitivity is defaut of your operating system
+    If iCaseSensitivity = 0, case sensitivity is default of your operating system
      (like 1 on Unix, 2 on Windows)
  */