patch 9.1.1065: no digraph for "Approaches the limit"

Problem:  no digraph for "Approaches the limit"
Solution: Add the digraph using .= (Hans Ginzel)

Add digraph Approaches the Limit

≐ U+2250 https://www.fileformat.info/info/unicode/char/2250/index.htm

closes: #16508

Signed-off-by: Hans Ginzel <hans@matfyz.cz>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/digraph.txt

@@ -1,4 +1,4 @@
-*digraph.txt*   For Vim version 9.1.  Last change: 2023 Oct 20
+*digraph.txt*   For Vim version 9.1.  Last change: 2025 Feb 02
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -125,8 +125,8 @@ see them.
 
 On most systems Vim uses the same digraphs.  They work for the Unicode and
 ISO-8859-1 character sets.  These default digraphs are taken from the RFC1345
-mnemonics.  To make it easy to remember the mnemonic, the second character has
-a standard meaning:
+mnemonics (with some additions).  To make it easy to remember the mnemonic,
+the second character has a standard meaning:
 
 	char name		char	meaning ~
 	Exclamation mark	!	Grave
@@ -1075,6 +1075,7 @@ char  digraph	hex	dec	official name ~
 ≅	?=	2245	8773	APPROXIMATELY EQUAL TO
 ≈	?2	2248	8776	ALMOST EQUAL TO
 ≌	=?	224C	8780	ALL EQUAL TO
+≐	.=	2250	8784	APPROACHES THE LIMIT
 ≓	HI	2253	8787	IMAGE OF OR APPROXIMATELY EQUAL TO
 ≠	!=	2260	8800	NOT EQUAL TO
 ≡	=3	2261	8801	IDENTICAL TO

runtime/doc/version9.txt

@@ -41635,6 +41635,7 @@ Changed~
 	"preinsert"	- highlight to be inserted values
 - add |dist#vim9#Launch()| and |dist#vim9#Open()| to the |vim-script-library|
   and decouple it from |netrw|
+- new digraph "APPROACHES THE LIMIT" using ".="
 
 							*added-9.2*
 Added ~