Handle permissions for `~/.gnupg/*gpg`

By default, gpg keyrings and configurations will have their permissions
locked down. The option `yadm.gpg-perms` can be used to disable.

yadm

@@ -356,6 +356,11 @@ function perms() {
     GLOBS=("${GLOBS[@]}" ".ssh" ".ssh/*")
   fi
 
+  #; include all gpg files (unless disabled)
+  if [[ $(config --bool yadm.gpg-perms) != "false" ]] ; then
+    GLOBS=("${GLOBS[@]}" ".gnupg" ".gnupg/*")
+  fi
+
   #; include globs found in YADM_ENCRYPT (if present)
   if [ -f "$YADM_ENCRYPT" ] ; then
     while IFS='' read -r glob || [ -n "$glob" ]; do

yadm.1

@@ -241,6 +241,11 @@ This feature is enabled by default.
 Disable the permission changes to
 .IR $HOME/.ssh/* .
 This feature is enabled by default.
+.TP
+.B yadm.gpg-perms
+Disable the permission changes to
+.IR $HOME/.gnupg/* .
+This feature is enabled by default.
 .SH ALTERNATES
 When managing a set of files across different systems, it can be useful to have
 an automated way of choosing an alternate version of a file for a different
@@ -307,9 +312,9 @@ configuration.
 Even if disabled, links can be manually created by running
 .BR yadm\ alt .
 .SH ENCRYPTION
-It can be useful to manage confidential files, like SSH keys, across multiple
-systems. However, doing so would put plain text data into a Git repository,
-which often resides on a public system.
+It can be useful to manage confidential files, like SSH or GPG keys, across
+multiple systems. However, doing so would put plain text data into a Git
+repository, which often resides on a public system.
 .B yadm
 implements a feature which can make it easy to encrypt and decrypt a set of
 files so the encrypted version can be maintained in the Git repository.
@@ -325,7 +330,8 @@ This list of patterns should be relative to the configured
 For example:
 
 .RS
-.BR \  .ssh/*.key
+    .ssh/*.key
+    .gnupg/*.gpg
 .RE
 
 The
@@ -363,6 +369,9 @@ The "group" and "others" permissions will be removed from the following files:
 - The SSH directory and files,
 .I .ssh/*
 
+- The GPG directory and files,
+.I .gnupg/*
+
 .B yadm
 will automatically update permissions by default. This can be disabled using the
 .I yadm.auto-perms