docs: Use preferred `languages` instead of deprecated `language` field (#22107)

uncenter created 

Ref
https://github.com/zed-industries/zed/issues/21994#issuecomment-2545988779,
`language` is already deprecated but was still suggested in the docs
here.

Release Notes:

- N/A

Change summary

docs/src/extensions/languages.md | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Detailed changes

docs/src/extensions/languages.md 🔗 

@@ -363,12 +363,12 @@ TBD: `#set! tag`
 
 Zed uses the [Language Server Protocol](https://microsoft.github.io/language-server-protocol/) to provide advanced language support.
 
-An extension may provide any number of language servers. To provide a language server from your extension, add an entry to your `extension.toml` with the name of your language server and the language it applies to:
+An extension may provide any number of language servers. To provide a language server from your extension, add an entry to your `extension.toml` with the name of your language server and the language(s) it applies to:
 
 ```toml
 [language_servers.my-language]
 name = "My Language LSP"
-language = "My Language"
+languages = ["My Language"]
 ```
 
 Then, in the Rust code for your extension, implement the `language_server_command` method on your extension: