Fix typos

lib/zdict.h

@@ -46,7 +46,7 @@ extern "C" {
  *
  * Zstd can use dictionaries to improve compression ratio of small data.
  * Traditionally small files don't compress well because there is very little
- * repetion in a single sample, since it is small. But, if you are compressing
+ * repetition in a single sample, since it is small. But, if you are compressing
  * many similar files, like a bunch of JSON records that share the same
  * structure, you can train a dictionary on ahead of time on some samples of
  * these files. Then, zstd can use the dictionary to find repetitions that are
@@ -132,7 +132,7 @@ extern "C" {
  *
  *   # Benchmark levels 1-3 without a dictionary
  *   zstd -b1e3 -r /path/to/my/files
- *   # Benchmark levels 1-3 with a dictioanry
+ *   # Benchmark levels 1-3 with a dictionary
  *   zstd -b1e3 -r /path/to/my/files -D /path/to/my/dictionary
  *
  * When should I retrain a dictionary?