refactor: rename content source dir

content/test.md

@@ -50,6 +50,10 @@ Lorem ipsum
 **dolor *sit*** amet \
 consectuer ~~что-то там~~.[^1]
 
+[Standalone link](https://dc09.ru/a)
+
+![Standalone image](https://dc09.ru/b)
+
 |Title| Price|Quantity|  Cost|
 |-----|-----:|-------:|-----:|
 |Abcde|115.23|   0.100| 11.52|

src/main.rs

@@ -9,7 +9,7 @@ use walkdir::WalkDir;
 
 fn main() {
     let src_dir = {
-        let def = || OsString::from("./source/");
+        let def = || OsString::from("./content/");
         let var = std::env::var_os("SOURCE_DIR").unwrap_or_else(def);
         PathBuf::from(var)
     };