tanru must be formed not only from gismu

[lagleki]

Describe the current content

When two gismu are adjacent, the first one modifies the second, and the selbri takes its place structure from the rightmost word. Such combinations of gismu are called 

https://la-lojban.github.io/uncll/uncll-1.2.16/xhtml_section_chunks/section-basic-tanru.html

This is misleading since not only gismu can form tanru
Proposed content

When two selbri (e.g. gismu) are adjacent, the first one modifies the second, they form a new bigger selbri and this resulting selbri takes its place structure from the rightmost word. Such combinations of selbri are called