docs: add help indexes (#2684)

* docs: add nvim-tree-index-api

* docs: add nvim-tree-index-opts

* docs: add nvim-tree-index-api

* docs: sort indices

* docs: less verbose

* docs: use dictionary sort for indices

scripts/help-update.sh

@@ -21,6 +21,39 @@ sed -e "s/^  /      /" /tmp/DEFAULT_OPTS.2.lua > /tmp/DEFAULT_OPTS.6.lua
 sed -i -e "/${begin}/,/${end}/{ /${begin}/{p; r /tmp/DEFAULT_OPTS.6.lua
            }; /${end}/p; d; }" doc/nvim-tree-lua.txt
 
+
+#
+# opts index
+#
+begin="nvim-tree-index-opts\*"
+end="====================="
+
+printf '\n' > /tmp/index-opts.txt
+sed -E "
+/^ *\*(nvim-tree\..*)\*$/! d ;
+s/^.*\*(.*)\*/|\1|/g
+" doc/nvim-tree-lua.txt | sort -d >> /tmp/index-opts.txt
+printf '\n' >> /tmp/index-opts.txt
+
+sed -i -e "/${begin}/,/${end}/{ /${begin}/{p; r /tmp/index-opts.txt
+           }; /${end}/p; d; }" doc/nvim-tree-lua.txt
+
+#
+# api index
+#
+begin="nvim-tree-index-api\*"
+end="====================="
+
+printf '\n' > /tmp/index-api.txt
+sed -E "
+/\*(nvim-tree-api.*\(\))\*/! d ;
+s/^.*\*(.*)\*/|\1|/g
+" doc/nvim-tree-lua.txt | sort -d >> /tmp/index-api.txt
+printf '\n' >> /tmp/index-api.txt
+
+sed -i -e "/${begin}/,/${end}/{ /${begin}/{p; r /tmp/index-api.txt
+           }; /${end}/p; d; }" doc/nvim-tree-lua.txt
+
 #
 # DEFAULT_ON_ATTACH
 #