Merge branch 'develop-rename-ros-2' into develop. Close #83.

**Description**

The code, the documentation, and the README use the terminology ROS2 to refer
to ROS 2.

The Open Source Robotics Foundation, Inc. (OSRF) has published specific
guidance on how the project should be referred to, and they have indicated that
they would want it to be called ROS 2.

**Type**

- Bug: wrong term used in documentation, help, manual.

**Additional context**

None.

**Requester**

- Ivan Perez

**Method to check presence of bug**

The following `grep` command finds all occurrences of ROS2:

```sh
$ grep -nIHre ROS2 --exclude='CHANGELOG.md'
ogma-cli/ogma-cli.cabal:70:                       <https://ros.org Robot Operating System (ROS2)>
ogma-cli/ogma-cli.cabal:94:                     >  ros                      Generate a ROS2 monitoring application
ogma-cli/ogma-cli.cabal:106:                     - <https://ros.org/ The Robot Operating System (ROS2) web page>.
ogma-cli/src/CLI/CommandROSApp.hs:84:commandDesc = "Generate a ROS2 monitoring package"
ogma-cli/README.md:120:  ros                      Generate a ROS2 monitoring package
```

Note that we exclude the CHANGELOGs because it does not make much sense to edit
old entries for this (it's likely better to be honest about what happened and
keep past entries as they are).

The following docker script prints `Success` if the text ROS2 is not found in
any files except for changelog files, and nothing otherwise.

```Dockerfile
FROM ubuntu:focal

RUN apt-get update

RUN apt-get install --yes git

SHELL ["/bin/bash", "-c"]
CMD git clone $REPO \
    && cd $NAME \
    && git checkout $COMMIT \
    && ! grep -nIHre 'ROS2' --exclude='CHANGELOG.md' \
    && echo "Success"
```

Command (substitute variables based on new path after merge):
```sh
$ docker run -e "REPO=https://github.com/NASA/ogma" -e "NAME=ogma" -e PAT="ogma-" -e "COMMIT=<HASH>" -it ogma-verify-83
```

**Expected result**

The command script prints "Success", indicating that no instances of ROS2 are
found.

**Solution implemented**

Rename all instances of ROS2 to ROS 2 in the code, the documentation, and the
README.

**Further notes**

None.

ogma-cli/CHANGELOG.md

@@ -1,5 +1,9 @@
 # Revision history for ogma-cli
 
+## [1.X.Y] - 2023-03-23
+
+* Rename ROS2 to ROS 2 (#83).
+
 ## [1.0.8] - 2023-03-21
 
 * Version bump 1.0.8 (#81).

ogma-cli/README.md

@@ -117,7 +117,7 @@ Available commands:
                            Specification
   fret-reqs-db             Generate a Copilot file from a FRET Requirements
                            Database
-  ros                      Generate a ROS2 monitoring package
+  ros                      Generate a ROS 2 monitoring package
 ```
 
 ## Language transformations: FRET

ogma-cli/ogma-cli.cabal

@@ -67,7 +67,7 @@ description:         Ogma is a tool to facilitate the integration of safe runtim
                        to a Copilot monitor.
                      .
                      - Generating
-                       <https://ros.org Robot Operating System (ROS2)>
+                       <https://ros.org Robot Operating System (ROS 2)>
                        applications that use Copilot for monitoring data
                        received from different topics.
                      .
@@ -91,7 +91,7 @@ description:         Ogma is a tool to facilitate the integration of safe runtim
                      >                           Specification
                      >  fret-reqs-db             Generate a Copilot file from a FRET Requirements
                      >                           Database
-                     >  ros                      Generate a ROS2 monitoring application
+                     >  ros                      Generate a ROS 2 monitoring application
                      .
                      For further information, see:
                      .
@@ -103,7 +103,7 @@ description:         Ogma is a tool to facilitate the integration of safe runtim
                      .
                      - <https://cfs.gsfc.nasa.gov/ The NASA Core Flight System web page>.
                      .
-                     - <https://ros.org/ The Robot Operating System (ROS2) web page>.
+                     - <https://ros.org/ The Robot Operating System (ROS 2) web page>.
                      .
                      - <https://ntrs.nasa.gov/citations/20200003164 "Copilot 3">, Perez, Dedden and Goodloe. 2020.
                      .

ogma-cli/src/CLI/CommandROSApp.hs

@@ -81,7 +81,7 @@ command c =
 
 -- | ROS command description
 commandDesc :: String
-commandDesc = "Generate a ROS2 monitoring package"
+commandDesc = "Generate a ROS 2 monitoring package"
 
 -- | Subparser for the @ros@ command, used to generate a Robot Operating System
 -- application connected to Copilot monitors.