Updates to Part 4: Hello Operators (was: Channels) (#408)

* Completed rewrite of the joint genotyping steps.

* Updated instructions/explanations across Hello Genomics and Hello Operators

* Updated intermediate workflow files for hello-genomics and hello-operators

* Changed some module and workflow names
    - Hello Science is now Hello Genomics
    - Hello Channels is now Hello Operators
    - hello-gatk.nf is now hello-genomics.nf

* Updated portal home index

* Updated console output labeling, line numbers etc

Co-authored-by: Marcel Ribeiro-Dantas <[email protected]>

Author: vdauwera

docs/hello_nextflow/01_orientation.md

@@ -65,14 +65,14 @@ You should see the following output:
 
 ```
 
-**The `data` directory** contains the input data we'll use in Part 3: Hello Science, which uses an example from genomics to demonstrate how to build a simple analysis pipeline.
+**The `data` directory** contains the input data we'll use in Part 3: Hello Genomics, which uses an example from genomics to demonstrate how to build a simple analysis pipeline.
 The data are described in detail in that section of the course.
 
 **The file `nextflow.config`** is a configuration file that sets minimal environment properties.
 
 **The file `hello-world.nf`** is a simple but fully functional workflow script that serves as a starting point to Part 1: Hello World.
 
-**The file `hello-gatk.nf`** is a stub that serves as a starting point to Part 3: Hello Science.
+**The file `hello-gatk.nf`** is a stub that serves as a starting point to Part 3: Hello Genomics.
 In its initial state, it is NOT a functional workflow script.
 
 **The remaining `.nf` files** are functional workflow scripts that serve as starting points for the corresponding parts of the course.

docs/hello_nextflow/02_hello_world.md

@@ -188,7 +188,7 @@ Have a look inside; you'll find a subdirectory named with a hash (in order to ma
 
     You should see something like this, though the exact subdirectory names will be different on your system.
 
-    ```console title="Output"
+    ```console title="Directory contents"
     work
     └── 1c
         └── 7d08e685a7aa7060b9c21667924824
@@ -904,7 +904,7 @@ For a complex workflow, or a large number of inputs, having the full list output
 
 That being said, we have another problem. If you look in the `results` directory, there are only two files: `output.txt` and `UPPER-output.txt`!
 
-```console title="Output"
+```console title="Directory contents"
 results
 ├── output.txt
 └── UPPER-output.txt
@@ -986,7 +986,7 @@ executor >  local (6)
 
 But more importantly, now we have six new files in addition to the two we already had in the `results` directory:
 
-```console title="Output"
+```console title="Directory contents"
 results
 ├── Bonjour-output.txt
 ├── Hello-output.txt