Rename `git-sugpatch` to `git-sugdiff`

The word "patch" reminds me more of the `patch` Unix command, which is
what `git-sugapply` does.

Since this command outputs diffs, it makes more sense to call it
`sugdiff`. That also brings these closer to the native Git commands,
`git-diff` and `git-apply`.

I had chosen "patch" originally because the command generated a unified
diff that could be used as a patch file to apply to the repo.

1 files changed, 70 insertions, 0 deletions

diff --git a/doc/git-sugdiff.1.txt b/doc/git-sugdiff.1.txt
new file mode 100644
index 0000000..9960949
--- /dev/null
+++ b/doc/git-sugdiff.1.txt
@@ -0,0 +1,70 @@
+git-sugdiff(1)
+==============
+
+NAME
+----
+git-sugdiff - Show diffs for GitHub suggestions
+
+SYNOPSIS
+--------
+'git sugdiff' [options] <suggestion>...
+
+DESCRIPTION
+-----------
+Show the diffs of the given GitHub suggestion references.
+
+A suggestion reference is either a URL to the comment, or its ID.
+
+OPTIONS
+-------
+--github-token=<token>::
+	A GitHub API token with the “repo” permission. This can also be set
+	with `githubSuggestion.githubToken` or the `GITHUB_TOKEN`
+	environment variable.
+
+-h, --help::
+	Print usage help.
+
+--remote=<remote-name>::
+	The remote to use to fetch the suggestion from when passing a
+	suggestion ID. This can also be set with `githubSuggestion.remote`.
+	Defaults to `origin`.
+
+-V, --version::
+	Print the program version.
+
+CONFIGURATION
+-------------
+Configuration options can be specified either as command line options,
+or in the Git config. Command line options take precedence.
+
+githubSuggestion.githubToken::
+	A GitHub API token with the “repo” permission. This will override
+	the `GITHUB_TOKEN` environment variable.
+
+githubSuggestion.remote::
+	The remote to use to fetch the suggestion from when passing a
+	suggestion ID. Defaults to `origin`.
+
+ENVIRONMENT VARIABLES
+---------------------
+GITHUB_TOKEN::
+	A GitHub API token with the “repo” permission.
+
+EXAMPLES
+--------
+Suggestion references can be specified either as URLs:
+
+	$ git sugdiff https://github.com/teddywing/git-suggestion/pull/1#discussion_r459691747
+
+or as comment IDs:
+
+	$ git sugdiff 459691747
+
+They can also be mixed:
+
+	$ git sugdiff 459692838 https://github.com/teddywing/git-suggestion/pull/1#discussion_r459691747
+
+SEE ALSO
+--------
+git-sugapply(1)