HPCC-11080 DOCS:Value Types link broken

Fix EPE-102 HPCC-11080 DOCS:Value Types link broken
Fix for the Value_Types link in the ECL Lang. Ref.
Issue itself was not a problem and did not manifest until
combining with other documents to produce the compiled help.
Each ID=attribute needs to be unique.

Signed-off-by: g-pan <greg.panagiotatos@lexisnexis.com>

@JamesDeFabia please review