Add size to filecount input (#4778)

plugins/inputs/filecount/README.md

@@ -8,8 +8,17 @@ Counts files in directories that match certain criteria.
 # Count files in a directory
 [[inputs.filecount]]
   ## Directory to gather stats about.
+  ##   deprecated in 1.9; use the directories option
   directory = "/var/cache/apt/archives"
 
+  ## Directories to gather stats about.
+  ## This accept standard unit glob matching rules, but with the addition of
+  ## ** as a "super asterisk". ie:
+  ##   /var/log/**    -> recursively find all directories in /var/log and count files in each directories
+  ##   /var/log/*/*   -> find all directories with a parent dir in /var/log and count files in each directories
+  ##   /var/log       -> count all files in /var/log and all of its subdirectories
+  directories = ["/var/cache/apt/archives"]
+
   ## Only count files that match the name pattern. Defaults to "*".
   name = "*.deb"
 
@@ -35,16 +44,17 @@ Counts files in directories that match certain criteria.
 
 - filecount
     - count (int)
+    - size_bytes (int)
 
 ### Tags:
 
 - All measurements have the following tags:
-    - directory (the directory path, as specified in the config)
+    - directory (the directory path)
 
 ### Example Output:
 
 ```
 $ telegraf --config /etc/telegraf/telegraf.conf --input-filter filecount --test
-> filecount,directory=/var/cache/apt,host=czernobog count=7i 1530034445000000000
-> filecount,directory=/tmp,host=czernobog count=17i 1530034445000000000
+> filecount,directory=/var/cache/apt,host=czernobog count=7i,size=7438336i 1530034445000000000
+> filecount,directory=/tmp,host=czernobog count=17i,size=28934786i 1530034445000000000
 ```