tpl: Do not write to cache when ignoring cache

Fixes #2067
Closes #2069

docs/content/extras/datadrivencontent.md

@@ -103,9 +103,8 @@ temporary directory.
 With the command-line flag `--cacheDir`, you can specify any folder on
 your system as a caching directory.
 
-If you don't like caching at all, you can fully disable to read from the
-cache with the command line flag `--ignoreCache`. However, Hugo will always
-write, on each build of the site, to the cache folder (silent backup).
+If you don't like caching at all, you can fully disable caching with the
+command line flag `--ignoreCache`.
 
 ### Authentication when using REST URLs
 

docs/content/overview/usage.md

@@ -48,7 +48,7 @@ Flags:
       --disableSitemap=false: Do not build Sitemap file
       --editor="": edit new content with this editor, if provided
   -h, --help=false: help for hugo
-      --ignoreCache=false: Ignores the cache directory for reading but still writes to it
+      --ignoreCache=false: Ignores the cache directory
       --log=false: Enable Logging
       --logFile="": Log File path (if set, logging enabled automatically)
       --noTimes=false: Don't sync modification time of files