add gemtext highlighting

vim/.vim/ftdetect/gemtext.vim

@@ -0,0 +1,4 @@
+" Vim file type detection for Gemtext markup
+
+au BufRead,BufNewFile *.gmi set filetype=gemtext
+au BufRead,BufNewFile *.gemini set filetype=gemtext

vim/.vim/syntax/gemtext.vim

@@ -0,0 +1,40 @@
+" Vim syntax file for Gemtext markup
+" as described by section 5 of the Gemini Specification
+" https://gemini.circumlunar.space/docs/specification.html
+
+if exists("b:current_syntax")
+    finish
+endif
+
+syntax sync fromstart
+
+syntax match gemtextLinkOperator '\v^\=\>' nextgroup=gemtextLinkURL skipwhite
+syntax match gemtextLinkURL '\v\S+' contained nextgroup=gemtextLinkText skipwhite
+syntax match gemtextLinkText '\v\S.*$' contained
+
+syntax match gemtextHeadingOperator '\v^\##?#?' nextgroup=gemtextHeadingText skipwhite
+syntax match gemtextHeadingText '\v\s*\S.*$' contained
+syntax match gemtextNotAHeadingOperator '\v^\####'
+
+syntax match gemtextUnorderedListItemOperator '\v^\*\s'
+
+syntax match gemtextQuoteOperator '\v^\>' nextgroup=gemtextQuoteText skipwhite
+syntax match gemtextQuoteText '\v.*$' contained
+
+syntax region gemtextPreformatBlock start="\v^```.*$" end="\v^```" keepend
+
+let b:current_syntax = "gemtext"
+
+hi def link gemtextLinkOperator Operator
+hi def link gemtextLinkURL Underlined
+hi def link gemtextLinkText String
+
+hi def link gemtextHeadingOperator Operator
+hi def link gemtextHeadingText Identifier
+
+hi def link gemtextUnorderedListItemOperator Operator
+
+hi def link gemtextQuoteOperator Operator
+hi def link gemtextQuoteText String
+
+hi def link gemtextPreformatBlock PreProc