add docs.

include/Support/Filesystem.h

@@ -1,9 +1,24 @@
 #pragma once
 
+#include <cstdio>
 #include <filesystem>
 
 namespace clice {
 
 namespace fs = std::filesystem;
 
+inline std::string readAll(std::string_view path) {
+    std::string result;
+    FILE* file = fopen(path.data(), "r");
+    if(file) {
+        fseek(file, 0, SEEK_END);
+        size_t size = ftell(file);
+        result.resize(size);
+        fseek(file, 0, SEEK_SET);
+        fread(result.data(), 1, size, file);
+        fclose(file);
+    }
+    return result;
 }
+
+}  // namespace clice