Rename chapters into "internals" and "intro"

levels/intro/commit

@@ -0,0 +1,28 @@
+title = "fu"
+
+[description]
+
+So you've been working on a project for a while, and decide you want to put it in a Git repository.
+
+Here's how to do it! First, you initialize a new Git repository in your current directory:
+
+    git init
+
+Then say that you want to record the current state of all files:
+
+    git add .
+
+And then you make a commit, which gives the current state a description, a date, and your name:
+
+    git commit
+
+[setup]
+
+mkdir recipes
+echo -e "blueberries\nflour" > recipes/blueberry_cake.txt
+echo -e "water\ncarrots" > recipes/carrot soup.txt
+echo "Very good recipes!" > README.md
+
+[win]
+
+test "$(git rev-parse HEAD^{tree})" = 1e02e3151284d0e22cd9b07ca5c5dbae2f3cb521

levels/intro/pull-merge-push

@@ -0,0 +1,32 @@
+title = A pull and a conflict
+author = blinry
+
+[description]
+
+You want to push your new commits to the server, but someone has already pushed their own changes.
+
+In this situation, you need to pull first! Try that here - you'll have to resolve a merge conflict. Push your changes afterwards.
+
+[congrats]
+
+Good job! Here's some additional info: banana!
+
+[setup yours]
+
+echo fu > file
+git add .
+git commit -m "Initial commit"
+git push
+
+echo fi > file
+git commit -a -m "Fi is good"
+
+[setup origin]
+
+echo fa > file
+git add .
+git commit -a -m "Fa is good"
+
+[win origin]
+
+test "$(git rev-parse HEAD^1^)" = "$(git rev-parse HEAD^2^)"

levels/intro/rebase

@@ -0,0 +1,20 @@
+description = Rebase all branches on top of the main branch, so that the commits are in alphabetical order, and then point the main branch to the top commit.
+
+[setup]
+
+git commit --allow-empty -m A
+git commit --allow-empty -m B
+git commit --allow-empty -m C
+
+git switch -c side1 main~1
+git commit --allow-empty -m D
+git commit --allow-empty -m E
+
+git switch -c side2 main~2
+git commit --allow-empty -m F
+
+git checkout main
+
+[win]
+
+diff <(git log --pretty=%s main) <(echo -e "F\nE\nD\nC\nB\nA")

levels/intro/sandbox

@@ -0,0 +1,8 @@
+[setup local]
+
+git commit --allow-empty -m "1"
+git commit --allow-empty -m "2"
+git commit --allow-empty -m "3"
+git push
+
+[setup origin]

levels/intro/sequence

@@ -0,0 +1 @@
+sandbox