Fix BPE bonus materials (#561)

* Fix BPE bonus materials

* fix bpe implementation

* update

* Add 'Hello, world. Is this-- a test?' test case

* update link to test file

* update path handling

* update path handling

* fix pytest paths

.gitignore

@@ -1,3 +1,4 @@
+
 # Configs and keys
 ch05/07_gpt_to_llama/config.json
 ch07/02_dataset-utilities/config.json
@@ -63,6 +64,8 @@ ch07/01_main-chapter-code/Smalltestmodel-sft-standalone.pth
 ch07/01_main-chapter-code/gpt2/
 
 # Datasets
+the-verdict.txt
+
 appendix-E/01_main-chapter-code/sms_spam_collection.zip
 appendix-E/01_main-chapter-code/sms_spam_collection
 appendix-E/01_main-chapter-code/train.csv
@@ -70,6 +73,7 @@ appendix-E/01_main-chapter-code/test.csv
 appendix-E/01_main-chapter-code/validation.csv
 
 ch02/01_main-chapter-code/number-data.txt
+ch02/05_bpe-from-scratch/the-verdict.txt
 
 ch05/03_bonus_pretraining_on_gutenberg/gutenberg
 ch05/03_bonus_pretraining_on_gutenberg/gutenberg_preprocessed
@@ -107,7 +111,9 @@ ch02/05_bpe-from-scratch/bpe_merges.txt
 ch02/05_bpe-from-scratch/encoder.json
 ch02/05_bpe-from-scratch/vocab.bpe
 ch02/05_bpe-from-scratch/vocab.json
-
+encoder.json
+vocab.bpe
+vocab.json
 
 # Other
 ch0?/0?_user_interface/.chainlit/