Update submit50.md

submit50.md

@@ -5,8 +5,6 @@
 When you run `submit50`, your files are "pushed" (i.e., uploaded) to CS50's "organization" (also named "submit50") on [GitHub](https://github.com/), a popular service via which developers (like you!) can share code. Your files are stored in a "repository" (a folder, essentially) to which only you and some of CS50's staff have access (and anyone else to whom you grant access). Your work can thus be reviewed and scored in one central place, whether you wrote it in [CS50 IDE](https://cs50.io/) or elsewhere!
 
 ## Installation
-
-1. Install [Docker](docker), if you haven't already.
 1. Install [Python 3.6](python) or later, if you haven't already.
 1. Install [`pip`](pip), if you haven't already.
 1. Install `submit50` itself:
@@ -23,14 +21,16 @@ pip install --upgrade submit50
 ## Usage
 
 ```
-usage: submit50 [-h] [-v] slug
+usage: submit50 [-h] [--logout] [-v] [-V] slug
 
 positional arguments:
   slug           prescribed identifier of work to submit
 
 optional arguments:
   -h, --help     show this help message and exit
+  --logout       logout of submit50
   -v, --verbose  show commands being executed
+  -V, --version  show program's version number and exit
 ```
 
 ## Examples
@@ -51,20 +51,18 @@ By default, `submit50` pushes your work to GitHub via HTTPS, which requires your
 
 1. [Generate an SSH key and add it to `ssh-agent`](https://help.github.com/articles/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent/).
 1. [Add the SSH key to your GitHub acount](https://help.github.com/articles/adding-a-new-ssh-key-to-your-github-account/).
-1. Execute
-   ```
-   git config --global credential.https://github.com/submit50.username jharvard
-   ```
-   where `jharvard` is your own GitHub username, which should add lines like the below to your `.gitconfig` so that `submit50` knows your GitHub username.
-   ```
-   [credential "https://github.com/submit50"]
-       username = jharvard
    ```
 1. Execute 
    ```
    ssh git@github.com
    ```
-   to add `github.com` to the list of known hosts for `ssh`, answering "yes" if prompted whether you're sure you want to continue connecting. 
+   to add `github.com` to the list of known hosts for `ssh`, answering "yes" if prompted whether you're sure you want to continue connecting. If all goes well, you should see the message
+
+    ```   
+    Hi <USERNAME>! You've successfully authenticated, but GitHub does not provide shell access.
+    Connection to github.com closed.
+    ```
+  (where `<USERNAME>` is your GitHub username).
 
 Thereafter, you should be able to run `submit50` without ever being prompted for your GitHub username or password. 
 
@@ -98,7 +96,7 @@ Nope, `submit50` uses its own `GIT_DIR` (in `/tmp`). It will ignore any `.git` d
 
 ### How does `submit50` remember my GitHub password?
 
-So that you need only type it once per week, `submit50` remembers your username and password in RAM using [`git-credential-cache`](https://git-scm.com/docs/git-credential-cache/).
+`submit50` remembers your username and password in RAM using [`git-credential-cache`](https://git-scm.com/docs/git-credential-cache/). Your password is never stored on disk or transmitted elsewhere.
 
 ## Source Code