Add gherkin syntax highlighting (helix-editor#11083)

Co-authored-by: Blaž Hrastnik <blaz@mxxn.io>

book/src/generated/lang-support.md

@@ -58,6 +58,7 @@
 | gas | ✓ | ✓ |  |  |
 | gdscript | ✓ | ✓ | ✓ |  |
 | gemini | ✓ |  |  |  |
+| gherkin | ✓ |  |  |  |
 | git-attributes | ✓ |  |  |  |
 | git-commit | ✓ | ✓ |  |  |
 | git-config | ✓ |  |  |  |

languages.toml

@@ -3764,6 +3764,17 @@ grammar = "typescript"
 "(" = ")"
 '"' = '"'
 
+[[language]]
+name = "gherkin"
+scope = "source.feature"
+file-types = ["feature"]
+comment-token = "#"
+indent = { tab-width = 2, unit = "  " }
+
+[[grammar]]
+name = "gherkin"
+source = { git = "https://github.com/SamyAB/tree-sitter-gherkin", rev = "43873ee8de16476635b48d52c46f5b6407cb5c09" }
+
 [[language]]
 name = "thrift"
 scope = "source.thrift"
@@ -3774,5 +3785,4 @@ indent = { tab-width = 2, unit = "  " }
 
 [[grammar]]
 name = "thrift"
-source = { git = "https://github.com/tree-sitter-grammars/tree-sitter-thrift" , rev = "68fd0d80943a828d9e6f49c58a74be1e9ca142cf" }
-
+source = { git = "https://github.com/tree-sitter-grammars/tree-sitter-thrift" , rev = "68fd0d80943a828d9e6f49c58a74be1e9ca142cf" }

runtime/queries/gherkin/highlights.scm

@@ -0,0 +1,17 @@
+[
+  (feature_keyword)
+  (rule_keyword)
+  (background_keyword)
+  (scenario_keyword)
+  (given_keyword)
+  (when_keyword)
+  (then_keyword)
+  (and_keyword)
+  (but_keyword)
+  (asterisk_keyword)
+] @keyword
+
+(tag) @function
+(doc_string) @string
+(data_table) @special
+(comment) @comment