Misc. ./samples typos

Found via `codespell -q 3 --skip="./3rdparty" -I ../opencv-whitelist.txt`

samples/cpp/detect_blob.cpp

@@ -118,7 +118,7 @@ int main(int argc, char *argv[])
     help();
 
 
-    // This descriptor are going to be detect and compute BLOBS with 6 differents params
+    // These descriptors are going to be detecting and computing BLOBS with 6 different params
     // Param for first BLOB detector we want all
     typeDesc.push_back("BLOB");    // see http://docs.opencv.org/trunk/d0/d7a/classcv_1_1SimpleBlobDetector.html
     pBLOB.push_back(pDefaultBLOB);