Fix colab link and improve wording (#288)

docs/source/getting-started.md

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+# Getting Started
+
+PySAGES is designed to seamlessly integrate with your existing simulations.
+For an easy start, we prepared examples in Google Colab notebooks, which provide
+access to a working simulation environment and GPU hardware.
+For example, you can use PySAGES with HOOMD-blue to run a simple [umbrella sampling
+simulation][HOOMD Notebook].
+Or, you can use PySAGES with OpenMM to explore the free energy landscape of the
+conformational space of alanine dipeptide via [harmonic biasing][OpenMM Notebook].
+Using the notebooks enables you to get started with PySAGES without any installation.
+However, for a more productive deployment, we recommend a local installation instead.
+
+We offer more examples, in the form of both Google Colab notebooks and scripts, for locally
+installed PySAGES in the [examples path][Examples URL] within the GitHub repository.
+
+<!-- References -->
+
+[HOOMD Notebook]: https://colab.research.google.com/github/SSAGESLabs/PySAGES/blob/main/examples/hoomd-blue/umbrella_integration/Umbrella_Integration.ipynb
+[OpenMM Notebook]: https://colab.research.google.com/github/SSAGESLabs/PySAGES/blob/main/examples/openmm/Harmonic_Bias.ipynb
+[Examples URL]: https://github.com/SSAGESLabs/PySAGES/tree/main/examples