added an explanation how to download and use the protobuf-compiler from the

github-release, in case the distribution version is not working (or the user
is not on an ubuntu system)

research/object_detection/g3doc/installation.md

@@ -48,10 +48,9 @@ pip install --user jupyter
 pip install --user matplotlib
 ```
 
-Note that sometimes "sudo apt-get install protobuf-compiler" will install
+**Note**: sometimes "sudo apt-get install protobuf-compiler" will install
 Protobuf 3+ versions for you and some users have issues when using 3.5.
-If that is your case, you're suggested to download and install Protobuf 3.0.0
-(available [here](https://github.com/google/protobuf/releases/tag/v3.0.0)).
+If that is your case, try the [manual](#Manual-protobuf-compiler-installation-and-usage) installation.
 
 ## COCO API installation
 
@@ -85,6 +84,21 @@ the tensorflow/models/research/ directory:
 protoc object_detection/protos/*.proto --python_out=.
 ```
 
+**Note**: If you're getting errors while compiling, you might be using an incompatible protobuf compiler. If that's the case, use the following manual installation
+
+## Manual protobuf-compiler installation and usage
+Download and install the 3.0 release of protoc, then unzip the file.
+```bash
+wget -O protobuf.zip https://github.com/google/protobuf/releases/download/v3.0.0/protoc-3.0.0-linux-x86_64.zip
+unzip protobuf.zip
+```
+
+Run the compilation process again, but use the downloaded version of protoc
+
+```bash
+./bin/protoc object_detection/protos/*.proto --python_out=.
+```
+
 ## Add Libraries to PYTHONPATH
 
 When running locally, the tensorflow/models/research/ and slim directories