refactor: messages for deploy|retrieve in md format (#332)

* fix: edit messages

* fix: update with info about metadata format

Author: jshackell-sfdc

messages/deploy.metadata.md

@@ -1,11 +1,13 @@
 # summary
 
-Deploy metadata in source format to an org from your local project.
+Deploy metadata to an org from your local project.
 
 # description
 
 You must run this command from within a project.
 
+Metadata components are deployed in source format by default. Deploy them in metadata format by specifying the --metadata-dir flag, which specifies the root directory or ZIP file that contains the metadata formatted files you want to deploy.
+
 If your org allows source tracking, then this command tracks the changes in your source. Some orgs, such as production org, never allow source tracking. You can also use the "--no-track-source" flag when you create a scratch or sandbox org to disable source tracking.
 
 To deploy multiple metadata components, either set multiple --metadata <name> flags or a single --metadata flag with multiple names separated by spaces. Enclose names that contain spaces in one set of double quotes. The same syntax applies to --manifest and --source-dir.

messages/retrieve.metadata.md

@@ -1,11 +1,13 @@
 # summary
 
-Retrieve metadata in source format from an org to your local project.
+Retrieve metadata from an org to your local project.
 
 # description
 
 You must run this command from within a project.
 
+Metadata components are retrieved in source format by default. Retrieve them in metadata format by specifying the --target-metadata-dir flag, which retrieves the components into a ZIP file in the specified directory.
+
 If your org allows source tracking, then this command tracks the changes in your source. Some orgs, such as production org, never allow source tracking. You can also use the "--no-track-source" flag when you create a scratch or sandbox org to disable source tracking.
 
 To retrieve multiple metadata components, either use multiple --metadata <name> flags or use a single --metadata flag with multiple names separated by spaces. Enclose names that contain spaces in one set of double quotes. The same syntax applies to --manifest and --source-dir.
@@ -51,11 +53,11 @@ To retrieve multiple metadata components, either use multiple --metadata <name>
   <%= config.bin %> <%= command.id %> --package-name Package1 "PackageName With Spaces" Package3
   <%= config.bin %> <%= command.id %> --package-name Package1 --package-name "PackageName With Spaces" --package-name Package3
 
-- Retrieve using Metadata API
+- Retrieve the metadata components listed in the force-app directory, but retrieve them in metadata format into a ZIP file in the "output" directory:
 
   <%= config.bin %> <%= command.id %> --source-dir force-app --target-metadata-dir output
 
-- Retrieve using Metadata API and automatically unzip the contents
+-  Retrieve in metadata format and automatically extract the contents into the "output" directory:
 
   <%= config.bin %> <%= command.id %> --source-dir force-app --target-metadata-dir output --unzip
 
@@ -125,7 +127,7 @@ Indicates that the zip file points to a directory structure for a single package
 
 # flags.target-metadata-dir.summary
 
-Directory root for the retrieved files.
+Directory that will contain the retrieved metadata format files or ZIP.
 
 # flags.unzip.summary