demos: update, replace branch with bookmark

The replacement is not purely mechanical, some text is also adjusted to
talk about bookmarks.

demos/demo_git_compat.sh

@@ -10,12 +10,12 @@ run_command "cd Hello-World"
 
 blank
 
-comment "By default, \"jj\" creates a local master branch tracking the remote master
-branch. The other branches are only available as remote-tracking branches."
-run_command "jj branch list --all"
-comment "We can create a local branch tracking one of the remote branches we just
+comment "By default, \"jj\" creates a local bookmark \"master\" tracking the remote master
+branch. Other remote branches are only available as remote-tracking bookmarks."
+run_command "jj bookmark list --all"
+comment "We can create a local bookmark tracking one of the remote branches we just
 fetched."
-run_command "jj branch track octocat-patch-1@origin"
+run_command "jj bookmark track octocat-patch-1@origin"
 
 comment "By default, \"jj log\" excludes untracked remote branches to focus on
 \"our\" commits."

demos/demo_juggle_conflicts.sh

@@ -6,13 +6,13 @@ new_tmp_dir
 (
     jj init --config-toml ui.allow-init-native=true
     echo "first" > file
-    jj branch create first
+    jj bookmark create first
     jj commit -m 'first'
     echo "second" > file
-    jj branch create second
+    jj bookmark create second
     jj commit -m 'second'
     echo "third" > file
-    jj branch create third
+    jj bookmark create third
     jj commit -m 'third'
 ) >/dev/null 2>&1
 

demos/demo_operation_log.sh

@@ -7,8 +7,8 @@ new_tmp_dir
     jj git clone https://github.com/octocat/Hello-World
     cd Hello-World
     jj abandon --ignore-immutable octocat-patch-1@origin
-    jj branch forget octocat-patch-1
-    jj branch track test@origin
+    jj bookmark forget octocat-patch-1
+    jj bookmark track test@origin
 } > /dev/null 2>&1
 
 comment "We are in the octocat/Hello-World repo.
@@ -18,7 +18,7 @@ run_command "jj op log"
 
 comment "We are going to make some changes to show
 how the operation log works. Let's add a file, set
-a description, and rebase onto the \"test\" branch:"
+a description, and rebase onto the \"test\" bookmark:"
 run_command "echo stuff > new-file"
 run_command "jj describe -m stuff"
 run_command "jj rebase -d test"

demos/demo_resolve_conflicts.sh

@@ -7,11 +7,11 @@ new_tmp_dir
     jj git clone https://github.com/octocat/Hello-World 
     cd Hello-World
     jj abandon --ignore-immutable test@origin
-    jj branch forget test
+    jj bookmark forget test
 } > /dev/null 2>&1
 
-comment "We are on the master branch of the
-octocat/Hello-World repo:"
+comment "We are on the master branch of the octocat/Hello-World repo,
+represented by the \"master\" bookmark on the parent commit."
 run_command "jj log"
 
 comment "Let's make an edit that will conflict

demos/demo_working_copy.sh

@@ -7,9 +7,9 @@ new_tmp_dir
     jj git clone https://github.com/octocat/Hello-World
     cd Hello-World
     jj abandon --ignore-immutable test@origin
-    jj branch forget test
+    jj bookmark forget test
     jj abandon --ignore-immutable octocat-patch-1@origin
-    jj branch forget octocat-patch-1
+    jj bookmark forget octocat-patch-1
 }> /dev/null 2>&1
 
 comment "We are in the octocat/Hello-World repo.
@@ -25,9 +25,9 @@ comment "Because of these changes, our working copy is no longer marked as \"(em
 Also, its commit ID (starting with a blue character) changed:"
 run_command "jj status"
 
-comment "Add a branch so we can easily refer to this
+comment "Add a bookmark so we can easily refer to this
 commit:"
-run_command "jj branch create goodbye"
+run_command "jj bookmark create goodbye"
 run_command "jj log"
 
 comment "Start working on a new change off of master:"