Merge branch 'tz/build-tech-midx-doc'

A documentation page that is referred to by other pages was not
built by mistake, which has been corrected.

* tz/build-tech-midx-doc:
  Documentation: build technical/multi-pack-index

Author: gitster

Documentation/Makefile

@@ -73,6 +73,7 @@ TECH_DOCS += technical/hash-function-transition
 TECH_DOCS += technical/http-protocol
 TECH_DOCS += technical/index-format
 TECH_DOCS += technical/long-running-process-protocol
+TECH_DOCS += technical/multi-pack-index
 TECH_DOCS += technical/pack-format
 TECH_DOCS += technical/pack-heuristics
 TECH_DOCS += technical/pack-protocol