vim-patch:9.1.1252: typos in code and docs related to 'diffopt' "inline:" (#33143)

Problem:  Typos in code and docs related to 'diffopt' "inline:".
          (after v9.1.1243)
Solution: Fix typos and slightly improve the docs.
          (zeertzjq)

closes: vim/vim#16997

5a307c361c

src/nvim/options.lua

@@ -2279,8 +2279,8 @@ local options = {
         			none    Do not perform inline highlighting.
         			simple  Highlight from first different
         				character to the last one in each
-        				line. This is the default if nothing
-        				is set.
+        				line.  This is the default if no
+        				`inline:` value is set.
         			char    Use internal diff to perform a
         				character-wise diff and highlight the
         				difference.