Fix the documentation formatting

There's no lexer for `grammar` supported by Jekyll, custom styles such as
`{.good}` are also not supported.

PiperOrigin-RevId: 178615029

site/docs/skylark/spec.md

diff --git a/site/docs/skylark/spec.md b/site/docs/skylark/spec.md
index a7ba6a6..8c6ab5d 100644
--- a/site/docs/skylark/spec.md
+++ b/site/docs/skylark/spec.md
@@ -1155,7 +1155,7 @@
 
 ### Identifiers
 
-```text {.good}
+```text
 Primary = identifier
 ```