Describe how to reword the most recent commit message

This is useful for when you realize that you forgot to mention
something important, made a typo, etc.  Obviously you should avoid
using this on a commit which you have already pushed.

Signed-off-by: Eric James Michael Ritz <ejmr@plutono.com>

README.md

@@ -19,6 +19,7 @@
 * [Delete local branch](https://github.com/git-tips/tips#delete-local-branch)
 * [Delete remote branch](https://github.com/git-tips/tips#delete-remote-branch)
 * [Undo local changes with the last content in head](https://github.com/git-tips/tips#undo-local-changes-with-the-last-content-in-head)
+* [Reword the previous commit message](https://github.com/git-tips/tips#reword-the-previous-commit-message)
 * [Changing a remote's URL](https://github.com/git-tips/tips#changing-a-remotes-url)
 * [Get list of all remote references](https://github.com/git-tips/tips#get-list-of-all-remote-references)
 * [Get list of all local and remote branches](https://github.com/git-tips/tips#get-list-of-all-local-and-remote-branches)
@@ -130,6 +131,11 @@ git push origin :<remote_branchname>
 git checkout -- <file_name>
 ```
 
+## Reword the previous commit message
+```sh
+git commit -v --amend
+```
+
 ## Changing a remote's URL
 ```sh
 git remote set-url origin <URL>

tips.json

@@ -64,6 +64,10 @@
       "title": "Undo local changes with the last content in head",
       "tip": "git checkout -- <file_name>"
   },
+  {
+      "title": "Reword the previous commit message",
+      "tip": "git commit -v --amend"
+  },
   {
       "title": "Changing a remote's URL",
       "tip": "git remote set-url origin <URL>"