Merge pull request #769 from tj-actions/chore/update-readme

Updated README.md

README.md

@@ -170,7 +170,7 @@ Support this project with a :star:
 |               path                | string |  false   |         `"."`         |                                                         Specify a relative path under<br>`$GITHUB_WORKSPACE` to locate the repository.<br>                                                         |
 |             quotepath             | string |  false   |       `"true"`        |                                      Use non ascii characters to<br>match files and output the<br>filenames completely verbatim by setting<br>this to `false`                                      |
 |             separator             | string |  false   |         `" "`         |                                                                               Split character for output strings<br>                                                                               |
-|                sha                | string |   true   | `"${{ github.sha }}"` |                                                                    Specify a different commit SHA<br>used for comparing changes                                                                    |
+|                sha                | string |  false   | `"${{ github.sha }}"` |                                                                    Specify a different commit SHA<br>used for comparing changes                                                                    |
 |               since               | string |  false   |                       |                                                         Get changed files for commits<br>whose timestamp is older than<br>the given time.                                                          |
 |               until               | string |  false   |                       |                                                        Get changed files for commits<br>whose timestamp is earlier than<br>the given time.                                                         |