docs: use fenced code blocks and enable syntax highlighting of toml snippets

docs/config.md

@@ -12,8 +12,10 @@ See the [TOML site](https://toml.io/en/) for more on syntax. One thing to
 remember is that anything under a heading can be dotted
 e.g. `user.name = "YOUR NAME"` is equivalent to:
 
+```toml
 [user]
 name = "YOUR NAME"
+```
 
 Headings only need to be set once in the real config file but Jujutsu favors the
 dotted style in these instructions, if only because it's easier to write down in
@@ -28,8 +30,10 @@ short if you ever need to check.
 
 ## User settings
 
+```toml
 user.name = "YOUR NAME"
 user.email = "YOUR_EMAIL@example.com"
+```
 
 Don't forget to change these to your own details!
 
@@ -42,18 +46,24 @@ Possible values are `always`, `never` and `auto` (default: `auto`).
 
 This setting overrides the `NO_COLOR` environment variable (if set).
 
+```toml
 ui.color = "never" # Turn off color
+```
 
 ### Shortest unique prefixes for ids
 
+```toml
 ui.unique-prefixes = "none"
+```
 
 Whether to highlight a unique prefix for commit & change ids. Possible values
 are `brackets` and `none` (default: `brackets`).
 
 ### Relative timestamps
 
+```toml
 ui.relative-timestamps = true
+```
 
 False by default, but setting to true will change timestamps to be rendered
 as `x days/hours/seconds ago` instead of being rendered as a full timestamp.
@@ -72,9 +82,11 @@ a `$`):
 
 You can define aliases for commands, including their arguments. For example:
 
+```toml
 # `jj l` shows commits on the working-copy commit's (anonymous) branch
 # compared to the `main` branch
 aliases.l = ["log", "-r", "(main..@): | (main..@)-"]
+```
 
 ## Editor
 
@@ -87,14 +99,19 @@ a `$`):
 Pico is the default editor in the absence of any other setting, but you could
 set it explicitly too.
 
+```toml
 ui.editor = "pico"
+```
 
 To use NeoVim instead:
 
+```toml
 ui.editor = "nvim"
+```
 
 For GUI editors you possibly need to use a `-w` or `--wait`. Some examples:
 
+```toml
 ui.editor = "code -w"       # VS Code
 ui.editor = "bbedit -w"     # BBEdit
 ui.editor = "subl -n -w"    # Sublime Text
@@ -102,6 +119,7 @@ For GUI editors you possibly need to use a `-w` or `--wait`. Some examples:
 ui.editor = ["C:/Program Files/Notepad++/notepad++.exe",
              "-multiInst", "-notabbar", "-nosession", "-noPlugin"] # Notepad++
 ui.editor = "idea --temp-project --wait"   #IntelliJ
+```
 
 Obviously, you would only set one line, don't copy them all in!
 
@@ -113,12 +131,16 @@ directories to diff are passed as the first and second argument respectively.
 
 For example:
 
+```toml
 ui.diff-editor = "kdiff3"
+```
 
 Custom arguments can be added, and will be inserted before the paths to diff:
 
+```toml
 # merge-tools.kdiff3.program = "kdiff3"      # Defaults to the name of the tool if not specified
 merge-tools.kdiff3.edit-args = ["--merge", "--cs", "CreateBakFiles=0"]
+```
 
 ### Using Vim as a diff editor
 
@@ -135,7 +157,9 @@ the [`DirDiff` Vim plugin].
 The `ui.merge-editor` key specifies the tool used for three-way merge tools
 by `jj resolve`. For example:
 
+```toml
 ui.merge-editor = "meld"  # Or "kdiff3" or "vimdiff"
+```
 
 The "meld", "kdiff3", and "vimdiff" tools can be used out of the box, as long as
 they are installed.
@@ -146,6 +170,7 @@ this key and other tool configuration options, here is the out-of-the-box
 configuration of the three default tools. (There is no need to copy it to your
 config file verbatim, but you are welcome to customize it.)
 
+```toml
 # merge-tools.kdiff3.program  = "kdiff3"     # Defaults to the name of the tool if not specified
 merge-tools.kdiff3.merge-args = ["$base", "$left", "$right", "-o", "$output", "--auto"]
 merge-tools.meld.merge-args   = ["$left", "$base", "$right", "-o", "$output", "--auto-merge"]
@@ -156,6 +181,7 @@ config file verbatim, but you are welcome to customize it.)
                                   "-c", "set write"]
 merge-tools.vimdiff.program = "vim"
 merge-tools.vimdiff.merge-tool-edits-conflict-markers = true    # See below for an explanation
+```
 
 `jj` replaces the following arguments with the appropriate file names:
 
@@ -200,13 +226,17 @@ The location of the `jj` config file can also be overriden with the
 to a TOML file that will be used instead of any configuration file in the
 default locations. For example,
 
+```shell
 env JJ_CONFIG=/dev/null jj log       # Ignores any settings specified in the config file.
+```
 
 You can use one or more `--config-toml` options on the command line to specify
 additional configuration settings. This overrides settings defined in config
 files or environment variables. For example,
 
+```shell
 jj --config-toml='ui.color="always"' --config-toml='ui.difftool="kdiff3"' split
+```
 
 Config specified this way must be valid TOML. In particular, string values must
 be surrounded by quotes. To pass these quotes to `jj`, most shells require
@@ -215,5 +245,6 @@ surrounding those quotes with single quotes as shown above.
 In `sh`-compatible shells, `--config-toml` can be used to merge entire TOML
 files with the config specified in `.jjconfig.toml`:
 
+```shell
 jj --config-toml="$(cat extra-config.toml)" log
-
+```