bitmap-format.txt: feed the file to asciidoc to generate html

Documentation/Makefile does not include bitmap-format.txt to generate
a html page using asciidoc.

Teach Documentation/Makefile to also generate a html page for
Documentation/technical/bitmap-format.txt file.

Signed-off-by: Abhradeep Chakraborty <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Abhra303

Documentation/Makefile

@@ -94,6 +94,7 @@ TECH_DOCS += MyFirstContribution
 TECH_DOCS += MyFirstObjectWalk
 TECH_DOCS += SubmittingPatches
 TECH_DOCS += ToolsForGit
+TECH_DOCS += technical/bitmap-format
 TECH_DOCS += technical/bundle-format
 TECH_DOCS += technical/hash-function-transition
 TECH_DOCS += technical/http-protocol