index.txt: Correct typos on landing page.

Conflicts:
	omero/index.txt
merge develop -D org -I include -E exclude: PR 450 (omero: Python 2.6 is the minimum supported version)
merge develop -D org -I include -E exclude: PR 462 (Adjusted titles of continuous integration developer pages (rebased onto develop))
merge develop -D org -I include -E exclude: PR 465 (index.txt: Correct typos on landing page.)