docs: document @keyword.control.exception scope
As identified in [this GitHub comment](https://github.com/helix-editor/helix/pull/1433#discussion_r777786140)
commit5b45bdd80f1b2bd456d247ed6d2d95e9efb9d304
authorEric Crosson <eric.s.crosson@utexas.edu>
dateMon 3 Jan 2022, 20:31 (5 years ago)
parent1c6bc6d
book/src/themes.md+1
@@ -147,6 +147,7 @@ We use a similar set of scopes as
147147 - `repeat` - `for`, `while`, `loop`
148148 - `import` - `import`, `export`
149149 - `return`
150+ - `exception`
150151 - `operator` - `or`, `in`
151152 - `directive` - Preprocessor directives (`#if` in C)
152153 - `function` - `fn`, `func`