Add Czech (cs) dictionary (#241)

The Czech Hunspell dictionary already exists in the blopker/dictionaries
fork but was not wired up in the code. This adds it to the
HUNSPELL_DICTIONARIES list and documents it in the README.

Author: mira-semera

README.md

@@ -264,6 +264,7 @@ Project-specific configuration is loaded from either `codebook.toml` or `.codebo
 # Default: ["en_us"]
 # Available dictionaries:
 #  - English: "en_us", "en_gb"
+#  - Czech: "cs"
 #  - German: "de", "de_at", "de_ch"
 #  - Dutch: "nl_nl"
 #  - Spanish: "es"

crates/codebook/src/dictionaries/repo.rs

@@ -59,6 +59,11 @@ static HUNSPELL_DICTIONARIES: LazyLock<Vec<HunspellRepo>> = LazyLock::new(|| {
             "https://raw.githubusercontent.com/blopker/dictionaries/refs/heads/main/dictionaries/en-GB/index.aff",
             "https://raw.githubusercontent.com/blopker/dictionaries/refs/heads/main/dictionaries/en-GB/index.dic",
         ),
+        HunspellRepo::new(
+            "cs",
+            "https://raw.githubusercontent.com/blopker/dictionaries/refs/heads/main/dictionaries/cs/index.aff",
+            "https://raw.githubusercontent.com/blopker/dictionaries/refs/heads/main/dictionaries/cs/index.dic",
+        ),
         HunspellRepo::new(
             "es",
             "https://raw.githubusercontent.com/blopker/dictionaries/refs/heads/main/dictionaries/es/index.aff",