NSIS: Possibility to include translated license and README.txt files (#14311)

* NSIS: Possibility to include translated license and README.txt files
* fixed a missing semicolon
* Disable always show dialog choice language

Signed-off-by: RestorerZ <restorer@mail2k.ru>
Signed-off-by: Christian Brabandt <cb@256bit.org>

nsis/lang/README.txt

@@ -0,0 +1,34 @@
+This directory contains a file with text strings for gVim installer.
+It also contains files with translations of the text strings for gVim installer
+into different languages.
+
+For translators.
+
+If you want to prepare a translation for the gVim installer, use the file
+"english.nsi" as a master file.  See the other translation files in this
+directory.
+Note that in the definition of the MUI_LANGUAGE macro, the name of the language
+to be translated must be the English name of the language.
+The name of the file with the translation must match the name of the target
+language.
+Also, when translating strings, pay attention to some restrictions on the
+allowable length of strings.  For example:
+ component description field - 117 characters;
+ description above the drop-down lists on the .vimrc page - 53 characters;
+ drop-down lists on the .vimrc page - 55 characters.
+Characters in this case mean characters of the English alphabet.
+
+If you do not yet have a translated "uganda.txt" file and a main "README.txt"
+file, set the following values:
+
+for the license file
+LicenseLangString page_lic_file 0 "${VIMRT}\doc\uganda.nsis.txt"
+
+for the readme.txt file
+LangString vim_readme_file 0 "README.txt"
+
+Once you have the translations of these files, then set the values for these
+variables similarly to what is done in the other translation files.
+Also add the appropriate entries to the "gvim.nsi" file as done for other
+languages.
+