docs: update explanation for token input (actions#125)

* chore(docs): Update explanation for token input

* docs: move token info to dedicated paragraph

* Fix typos

Co-authored-by: Federico Grandi <fgrandi30@gmail.com>

README.md

@@ -59,7 +59,7 @@ Add a step like this to your workflow:
     # Default: ''
     tag: 'v1.0.0 --force'
 
-    # Token to use for pushing the commit. The default value won't trigger any workflows, you need to use a Personal Access Token for that.
+    # The token to use to access the GitHub API when getting the author info (see the paragraph below for more info about the tokens used by the action)
     # Default: secrets.GITHUB_TOKEN
     token: ${{ secrets.GITHUB_TOKEN }}
 ```
@@ -91,6 +91,12 @@ One way to use this is if you want to force push to a branch of your repo: you'l
 
 You can use the `tag` option to enter the arguments for a `git add` command. In order for the action to isolate the tag name from the rest of the arguments, it should be the first word not preceded by an hyphen (e.g. `-a tag-name -m "some other stuff"` is ok).
 
+### Tokens:
+
+The token from the `token` input is only used when getting the author info from the GitHub API: usually the default GitHub token is enough but if for some reason you want to change it, you can use that input.  
+When pushing, the action uses the token that the local git repository has been configured with: that means that if you want to change it you'll need to do it in the steps that run before this action. For example: if you set up your repo with [`actions/checkout`](https://github.com/actions/checkout/) then you have to change the token there.  
+Changing the token with which the repo is configured can be useful if you want to run CI checks on the commit pushed by this action; anyway, it has to be set up outside of this action.
+
 ### Outputs:
 
 The action provides these outputs: