Added file with minimal knowledge to work with plugins

PluginsInfo.md

+# Overview
+# Installing
+## Installing wolf(core)
+```
+git clone https://gitlab.iri.upc.edu/mobile_robotics/wolf_projects/wolf_lib/plugins/core.git
+cd core
+mkdir build & cd build
+cmake ..
+make
+make install
+```
+## Installing plugins
+```
+git clone https://gitlab.iri.upc.edu/mobile_robotics/wolf_projects/wolf_lib/plugins/<plugin name>.git
+cd <plugin name>
+mkdir build & cd build
+cmake ..
+make
+make install
+```
+
+# Using wolf in your applications
+If you want to use the core, you just need to have it installed and in your CMakeLists.txt put the following line
+`find_package(wolf REQUIRED)`
+If wolf is indeed installed, this will define two variables
+`${wolf_INCLUDE_DIR}` which will contain the path to the wolf include directory
+and `${wolf_LIBRARY}` which will contain the path to the wolf library
+If you instead want to use some wolf plugin, you just follow the same procedure, changing the name
+`find_package(wolf<plugin name> REQUIRED)`
+If the pluging is indeed installed, this will define two variables
+`${wolf<plugin name>_INCLUDE_DIR}` which will contain the path to the plugin's include directory
+and `${wolf<plugin name>_LIBRARY}` which will contain the path to the plugin's library.
+
+As an example, suppose that we want to use the _vision_ plugin. First, we will clone and install it
+```
+git clone https://gitlab.iri.upc.edu/mobile_robotics/wolf_projects/wolf_lib/plugins/vision.git
+cd vision
+mkdir build && cd build
+cmake ..
+make
+sudo make install
+```
+Then, in the CMakeLists.txt of the application we are developing we will put the following line
+```
+find_package(wolfvision REQUIRED)
+```
+if the plugin has been correctly installed, and thus find_package succeeds, then it will define two variables
+
+- ${wolfvision_INCLUDE_DIR} which is the path to the includes. It should have the value `/usr/local/include/iri-algorithms/wolf/plugin_vision`
+- ${wolfvision_LIBRARY} which is the path to the compiled (& linked) library. It should have the value `/usr/local/lib/iri-algorithms/libwolfvision.so`
+
+*IMPORTANT NOTE* For the time being, each plugin is only responsible for finding their own includes and library. This means that for instance wolfvision, which obviously requires
+the _core_ plugin, will not find its own dependencies. It is the responsibility of the programmer to do `find_package(wolf REQUIRED)` to get the includes and library. In the future these will change, and each plugin will be responsible for finding all the necessary dependencies.
+
+# Creating your plugin
+We provide a template to create your own plugin.
+You can either clone it and restart the git history
+```
+git clone https://gitlab.iri.upc.edu/mobile_robotics/wolf_projects/wolf_lib/plugins/Template.git
+cd Template
+rm -rf .git
+git init
+```
+or directly fork*(?)* the repository.
+  
+# Contributing
+## Contributing your plugin to wolf
+## Contributing to existing plugins
+## Contributing to wolf core
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