Fix broken regex in doc tests

Regexes are hard.

docs/reference/cat/allocation.asciidoc

@@ -16,9 +16,9 @@ Might respond with:
 [source,js]
 --------------------------------------------------
 shards disk.indices disk.used disk.avail disk.total disk.percent host      ip        node
-     5         260b    47.3gb     53.4gb    100.7gb           46 127.0.0.1 127.0.0.1 CSUXak2
+     5         260b    47.3gb     43.4gb    100.7gb           46 127.0.0.1 127.0.0.1 CSUXak2
 --------------------------------------------------
-// TESTRESPONSE[s/260b/\\d+b/ s/\\d+(\\.\\d+)?[tmk]b?/\\d+(\\.\\d+)?[tmk]b?/ s/46/\\d+/]
+// TESTRESPONSE[s/260b/\\d+b/ s/\d+(\.\d+)?[tgmk]?b/\\d+(\\.\\d+)?[tgmk]?b/ s/46/\\d+/]
 // TESTRESPONSE[s/CSUXak2/.+/ _cat]
 
 Here we can see that each node has been allocated a single shard and