Add additional instructions to README and User Guide

[stephaniereinders]

• Add required packages from grooveFinder, x3ptools, and bulletxtrctr to the install list - add shinyscreenshot as an Import for bulletAnalyzr
• Change instructions to not use devtools
• Add common installation error messges
• Add summary of phase test results
• Add requirements for bullets

Change instructions to not use devtools

I ran devtools::install_github("heike/bulletxtrctr") on my Windows laptop and got the error message

"Using GitHub PAT from the git credential store.
Error: Failed to install 'unknown package' from GitHub:
HTTP error 401.
Bad credentials"

I don't have a PAT on this machine. Instead of instructing users to use devtools, give users instructions to download bulletxtrctr and x3ptools as ZIP files and build the packages in RStduio. Users need to install x3ptools first because it is required by bulletxtrctr.

Add common installation error messages

Example: I encountered this warning while trying to install the bsicons package on my Windows laptop.

"WARNING: Rtools is required to build R packages but is not currently installed. Please download and install the appropriate version of Rtools before proceeding:

https://cran.rstudio.com/bin/windows/Rtools/"

Example: I encountered this error after clicking Install on the Build tab of bulletAnalyzr-main.

"Error in load_imports(path) :
The packages "webshot2" and "pandoc" are required. Calls: suppressPackageStartupMessages ... load_imports -> deps_check_installed -> check_installed
Execution halted"