Add documentation about get_builder_from_protocol

This commit adds some general remarks about the `get_builder_from_protocol` methods in the `How to - Workflows` section.

docs/source/howto/workflows/index.md

@@ -2,6 +2,26 @@
 
 # Workflows
 
+## Default parameters
+
+The AiiDA Quantum ESPRESSO plugin comes with a set of tested protocols. These protocols define default input parameters for different levels of precision. This concept enables the initialization of a pre-populated `builder` for most of the different `WorkChain`s, which can be obtained by calling the `get_builder_from_protocol` method.
+
+The following example shows the working principle for the `PwBaseWorkChain`:
+
+```
+# code and structure are the mandatory input arguments
+
+builder = PwBaseWorkChain.get_builder_from_protocol(
+    code=pw_code, # load your pw-code
+    structure=structure, # provide your input structure here
+)
+
+```
+We refer to the documentation of the {{ get_builder_from_protocol }} method for further details about additional default input arguments.
+
+
+
+
 ```{toctree}
 :maxdepth: 1