cli help: add code blocks to make help render as markdown properly

cli/src/commands/next.rs

@@ -31,17 +31,20 @@ use crate::ui::Ui;
 /// The command moves you to the next child in a linear fashion.
 ///
 ///
+/// ```
 /// D      D @
 /// |      |/
 /// C @ => C
 /// |/     |
 /// B      B
+/// ```
 ///
 ///
 /// If `--edit` is passed, it will move you directly to the child
 /// revision.
 ///
 ///
+/// ```
 /// D    D
 /// |    |
 /// C    C
@@ -49,6 +52,7 @@ use crate::ui::Ui;
 /// B => @
 /// |    |
 /// @    A
+/// ```
 #[derive(clap::Args, Clone, Debug)]
 #[command(verbatim_doc_comment)]
 pub(crate) struct NextArgs {

cli/src/commands/prev.rs

@@ -25,18 +25,18 @@ use crate::ui::Ui;
 ///
 /// The command moves you to the parent in a linear fashion.
 ///
-///
+/// ```
 /// D @  D
 /// |/   |
 /// A => A @
 /// |    | /
 /// B    B
-///
+/// ```
 ///
 /// If `--edit` is passed, it will move the working copy commit
 /// directly to the parent.
 ///
-///
+/// ```
 /// D @  D
 /// |/   |
 /// C => @
@@ -44,6 +44,7 @@ use crate::ui::Ui;
 /// B    B
 /// |    |
 /// A    A
+/// ```
 // TODO(#2126): Handle multiple parents, e.g merges.
 #[derive(clap::Args, Clone, Debug)]
 #[command(verbatim_doc_comment)]

cli/src/commands/rebase.rs

@@ -46,6 +46,7 @@ use crate::ui::Ui;
 /// your history like this (letters followed by an apostrophe are post-rebase
 /// versions):
 ///
+/// ```
 /// O           N'
 /// |           |
 /// | N         M'
@@ -57,6 +58,7 @@ use crate::ui::Ui;
 /// | K         | K
 /// |/          |/
 /// J           J
+/// ```
 ///
 /// With `-b`, the command rebases the whole "branch" containing the specified
 /// revision. A "branch" is the set of commits that includes:
@@ -71,6 +73,7 @@ use crate::ui::Ui;
 /// -d O` would transform your history like this (because `L` and `M` are on the
 /// same "branch", relative to the destination):
 ///
+/// ```
 /// O           N'
 /// |           |
 /// | N         M'
@@ -82,12 +85,14 @@ use crate::ui::Ui;
 /// | K         O
 /// |/          |
 /// J           J
+/// ```
 ///
 /// With `-r`, the command rebases only the specified revision onto the
 /// destination. Any "hole" left behind will be filled by rebasing descendants
 /// onto the specified revision's parent(s). For example, `jj rebase -r K -d M`
 /// would transform your history like this:
 ///
+/// ```
 /// M          K'
 /// |          |
 /// | L        M
@@ -95,12 +100,14 @@ use crate::ui::Ui;
 /// | K        | L'
 /// |/         |/
 /// J          J
+/// ```
 ///
 /// Note that you can create a merge commit by repeating the `-d` argument.
 /// For example, if you realize that commit L actually depends on commit M in
 /// order to work (in addition to its current parent K), you can run `jj rebase
 /// -s L -d K -d M`:
 ///
+/// ```
 /// M          L'
 /// |          |\
 /// | L        M |
@@ -108,6 +115,7 @@ use crate::ui::Ui;
 /// | K        | K
 /// |/         |/
 /// J          J
+/// ```
 #[derive(clap::Args, Clone, Debug)]
 #[command(verbatim_doc_comment)]
 #[command(group(ArgGroup::new("to_rebase").args(&["branch", "source", "revision"])))]