make underline_style a seperate option

Underline styles are mutally exclusive and overwrite each other.
Therefore implementing as an modifier lead to incorrect behaviour
when the underline style is overwritten.

For backwards compatability the "underline" modified is retained (but
deprecated). Instead the "underline_style" and "underline_color"
optios should be used to style underlines.

1 files changed, 17 insertions, 6 deletions

diff --git a/book/src/themes.md b/book/src/themes.md
index 32ff2498..450b3364 100644
--- a/book/src/themes.md
+++ b/book/src/themes.md
@@ -13,10 +13,10 @@ The default theme.toml can be found [here](https://github.com/helix-editor/helix
 Each line in the theme file is specified as below:
 
 ```toml
-key = { fg = "#ffffff", bg = "#000000", underline = "#ff0000", modifiers = ["bold", "italic", "undercurled"] }
+key = { fg = "#ffffff", bg = "#000000", underline_color = "#ff0000", underline_style = "curl", modifiers = ["bold", "italic"] }
 ```
 
-where `key` represents what you want to style, `fg` specifies the foreground color, `bg` the background color, `underline` the underline color (only meaningful if an underline modifier is enabled), and `modifiers` is a list of style modifiers. `bg`, `underline` and `modifiers` can be omitted to defer to the defaults.
+where `key` represents what you want to style, `fg` specifies the foreground color, `bg` the background color, `underline_style` the underline style, `underline_color` the underline color (only meaningful if an underline style is enabled), and `modifiers` is a list of style modifiers. `bg`, `underline` and `modifiers` can be omitted to defer to the defaults.
 
 To specify only the foreground color:
 
@@ -83,16 +83,27 @@ Less common modifiers might not be supported by your terminal emulator.
 | `dim`                |
 | `italic`             |
 | `underlined`         |
-| `undercurled`        |
-| `underdashed`        |
-| `underdotted`        |
-| `double-underlined`  |
 | `slow_blink`         |
 | `rapid_blink`        |
 | `reversed`           |
 | `hidden`             |
 | `crossed_out`        |
 
+### Underline Style
+
+One of the following values may be used as an `underline_styles`. 
+
+Some styles might not be supported by your terminal emulator.
+
+| Modifier       |
+| ---            |
+| `line`         |
+| `curl`         |
+| `dashed`       |
+| `dot`          |
+| `double-line`  |
+
+
 ### Scopes
 
 The following is a list of scopes available to use for styling.