Merge pull request gitname#130 from gitname/110-add-note-about-branch…

…-names-master-main

Add note about branch names: `master` vs. `main`

README.md

@@ -83,6 +83,12 @@ At this point, your GitHub account contains an empty repository, having the name
 
     > In addition to containing the source code of the React app, that folder is also a Git repository. That characteristic of the folder will come into play in Step 6.
 
+    > #### Branch names: `master` vs. `main`
+    > 
+    > The Git repository will have one branch, which will be named either (a) `master`, the default for a fresh Git installation; or (b) the value of the Git configuration variable, `init.defaultBranch`, if your computer is running Git version 2.28 or later _and_ you have [set that variable](https://github.blog/2020-07-27-highlights-from-git-2-28/#introducing-init-defaultbranch) in your Git configuration (e.g. via `$ git config --global init.defaultBranch main`).
+    >
+    > Since I have not set that variable in my Git installation, the branch in my repository will be named `master`. In case the branch in your repository has a different name (which you can check by running  `$ git branch`), such as `main`; you can **replace** all occurrences of `master` throughout the remainder of this tutorial, with that other name (e.g. `master` → `main`).
+
 2. Enter the newly-created folder:
   
     ```shell