Add argument to set644 and set755 perms alias. (ohmyzsh#6959)

This can avoid big mistakes as this I just made.
I thought I could give it an argument. So, now, it is possible.

plugins/perms/README.md

@@ -4,6 +4,6 @@ Plugin to handle some unix filesystem permissions quickly
 
 ### Usage
 
-* `set755` recursively sets all directories located within the current working directory and sub directories to octal 755.
-* `set644` recursively sets all files located within the current working directory and sub directories to octal 644.
-* `fixperms` is a wrapper around `set755` and `set644` applied to a specified directory or the current directory otherwise. It also prompts prior to execution unlike the other two  aliases.
+* `set755` recursively sets all given directories (default to .) to octal 755.
+* `set644` recursively sets all given files (default to .) to octal 644.
+* `fixperms` is a wrapper around `set755` and `set644` applied to a specified directory or the current directory otherwise. It also prompts prior to execution unlike the other two  aliases.

plugins/perms/perms.plugin.zsh

@@ -6,10 +6,14 @@
 ### Aliases
 
 # Set all files' permissions to 644 recursively in a directory
-alias set644='find . -type f ! -perm 644 -print0 | xargs -0 chmod 644'
+set644() {
+	find "${@:-.}" -type f ! -perm 644 -print0 | xargs -0 chmod 644
+}
 
 # Set all directories' permissions to 755 recursively in a directory
-alias set755='find . -type d ! -perm 755 -print0 | xargs -0 chmod 755'
+set755() {
+	find "${@:-.}" -type d ! -perm 755 -print0 | xargs -0 chmod 755
+}
 
 ### Functions