Add instructions for adding a post

Author: cgoldberg

HOW-TO-POST.md

@@ -0,0 +1,17 @@
+# How-To Add a New Post
+
+Instructions:
+
+- clone the repo:
+  - `$ git clone [email protected]:cgoldberg/cgoldberg.github.io.git`
+- change directory to base of repo:
+  - `$ cd cgoldberg.github.io`
+- add new file to `./_posts/` with name format: `YYYY-MM-DD-post-title.md`
+- commit changes
+  - `$ git commit -a -m "commit message"`
+- push changes to GitHub:
+  - `$ git push`
+
+That's it! The GitHub actions workflow job will publish it to GitGHub Pages.
+
+View the post at: https://cgoldberg.github.io