grep: fix the grep example to cover all except target/
Find an area you can help with and do it. Open source is about collaboration and open participation. Try to make your code look like what already exists and submit a pull request.
-The [list of issues](https://github.com/mimblewimble/grin/issues) is a good place to start, especially the ones tagged as "help wanted" (but don't let that stop you from looking at others). If you're looking for additional ideas, the code includes `TODO` comments for minor to major improvements. Use _Search in files_ in your code editor, or `grep "TODO" -r src/`.
+The [list of issues](https://github.com/mimblewimble/grin/issues) is a good place to start, especially the ones tagged as "help wanted" (but don't let that stop you from looking at others). If you're looking for additional ideas, the code includes `TODO` comments for minor to major improvements. Use _Search in files_ in your code editor, or `grep "TODO" -r --exclude-dir=target --exclude-dir=.git .`.
Additional tests are rewarded with an immense amount of positive karma.
