Misc. typos

Found via `codespell -q 3` in  downstream https://github.com/BlueBrain/Brayns

example/archiver/archiver.h

@@ -97,7 +97,7 @@ private:
     // PIMPL
     void* mDocument;              ///< DOM result of parsing.
     void* mStack;                 ///< Stack for iterating the DOM
-    bool mError;                  ///< Whether an error is occured.
+    bool mError;                  ///< Whether an error has occurred.
 };
 
 class JsonWriter {

example/jsonx/jsonx.cpp

@@ -1,4 +1,4 @@
-// JSON to JSONx conversion exmaple, using SAX API.
+// JSON to JSONx conversion example, using SAX API.
 // JSONx is an IBM standard format to represent JSON as XML.
 // https://www-01.ibm.com/support/knowledgecenter/SS9H2Y_7.1.0/com.ibm.dp.doc/json_jsonx.html
 // This example parses JSON text from stdin with validation, 

example/parsebyparts/parsebyparts.cpp

@@ -143,7 +143,7 @@ int main() {
         AsyncDocumentParser<> parser(d);
 
         const char json1[] = " { \"hello\" : \"world\", \"t\" : tr";
-        //const char json1[] = " { \"hello\" : \"world\", \"t\" : trX"; // Fot test parsing error
+        //const char json1[] = " { \"hello\" : \"world\", \"t\" : trX"; // For test parsing error
         const char json2[] = "ue, \"f\" : false, \"n\": null, \"i\":123, \"pi\": 3.14";
         const char json3[] = "16, \"a\":[1, 2, 3, 4] } ";