fix link error in readme

Author: haoel

shell/README.md

@@ -3,7 +3,7 @@
 
 | # | Title | Solution | Difficulty |
 |---| ----- | -------- | ---------- |
-|4|[Tenth Line](https://leetcode.com/problems/tenth-line/)| [Bash](./shell/TenthLine.sh)|Easy|
-|3|[Transpose File](https://leetcode.com/problems/transpose-file/)| [Bash](./shell/TransposeFile.sh)|Medium|
-|2|[Valid Phone Numbers](https://leetcode.com/problems/valid-phone-numbers/)| [Bash](./shell/ValidPhoneNumbers.sh)|Easy|
-|1|[Word Frequency](https://leetcode.com/problems/word-frequency/)| [Bash](./shell/WordFrequency.sh)|Medium|
+|4|[Tenth Line](https://leetcode.com/problems/tenth-line/)| [Bash](./TenthLine.sh)|Easy|
+|3|[Transpose File](https://leetcode.com/problems/transpose-file/)| [Bash](./TransposeFile.sh)|Medium|
+|2|[Valid Phone Numbers](https://leetcode.com/problems/valid-phone-numbers/)| [Bash](./ValidPhoneNumbers.sh)|Easy|
+|1|[Word Frequency](https://leetcode.com/problems/word-frequency/)| [Bash](./WordFrequency.sh)|Medium|