minor #9252 Change value for opcache.memory_consumption (axzx)

This PR was submitted for the 4.0 branch but it was merged into the 2.7 branch instead (closes #9252).

Discussion
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Change value for opcache.memory_consumption

The size of the shared memory storage used by OPcache, in megabytes.

Commits
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ac7fae8 Change value for opcache.memory_consumption

Author: javiereguiluz

performance.rst

@@ -130,7 +130,7 @@ it's recommended to change these settings as follows:
 
     ; php.ini
     ; maximum memory that OPcache can use to store compiled PHP files
-    opcache.memory_consumption=256M
+    opcache.memory_consumption=256
 
     ; maximum number of files that can be stored in the cache
     opcache.max_accelerated_files=20000