Add a quick guide for adding new languages

Closes: #942

website/site/content/docs/dev/add-language.md

@@ -0,0 +1,68 @@
++++
+title = "Adding new language"
+weight = 30
++++
+
+# Adding a new language for document processing
+
+Then there are other commits and issues to look at:
+
+- [Add Spanish language](https://github.com/eikek/docspell/commit/26dff18ae0d32ce2b32b4d11ce381ada0e99314f)
+- [Add Latvian language](https://github.com/eikek/docspell/issues/679) and [PR](https://github.com/eikek/docspell/pull/694/commits/9991ad5fcc43ccefe011a6cc4d01bdae4bcd4573)
+- [Add Japanese language](https://github.com/eikek/docspell/issues/948) and [PR](https://github.com/eikek/docspell/pull/961/commits/f994d4b2488e64668ee064676f8c6469d9ccc1be), had some corrections: [1](https://github.com/eikek/docspell/commit/c59d4f8a6d021ec4b01a92320c211248503f16a5), [Issue](https://github.com/eikek/docspell/issues/973)
+- [Add Hebrew language](https://github.com/eikek/docspell/pull/1027)
+
+Some older commits may be a bit out of date, but still show the
+relevant things to do. These are:
+
+- add it to `Language.scala`, create a new `case object` and add it to
+  the `all` list (then fix compile errors)
+- define a list of month names to support date recognition and update
+  `DateFind.scala` to recognize date patterns for that language. Add
+  some tests to `DateFindTest`.
+- add it to joex' dockerfile to be available for tesseract
+- update the solr migration/field definitions in `SolrSetup`. Create a
+  new solr migration that adds the content field for the new
+  language - it is a copy&paste from other similar changes.
+- update `FtsRepository` for the PostgreSQL fulltext search variant:
+  if not sure, use `simple` here
+- update the elm file so it shows up on the client. Also requires to
+  add translations in `Messages.Data.Language`
+
+## Test
+
+Check if everything is fine with `sbt Test/compile`. After the project
+compiles without errors, run `sbt fix` to apply formatting fixes.
+
+It would be good to startup docspell and check the new lanugage a bit,
+including whether fulltext search is working.
+
+Sometimes, SOLR doesn't support a language. In this case the migration
+needs to first add the new *field type*. There are examples for
+Lithuanian and Hebrew in the code.
+
+For the docker image, you can run
+
+```bash
+PLATFORMS=linux/amd64 ./build.sh 0.36.0-SNAPSHOT
+```
+
+in `docker/dockerfile` directory to build the docker image (just
+choose some version, it doesn't matter).
+
+## Non-NLP only
+
+Note that this is without support for NLP. Including support for NLP
+means that the [stanford nlp](https://github.com/stanfordnlp/CoreNLP)
+library needs to provide models for it and these must be included in
+the build and tested a bit.
+
+## Opening issues on Github
+
+You can also open an issue on github requesting to support a language.
+I kindly ask to include all necessary information, like in
+[this](https://github.com/eikek/docspell/issues/1540) issue. I know
+that I can dig it out from websites, but it would be nice to have
+everything ready. Also it is better to know from a local person some
+details, like which date patterns are more likely to appear than
+others.

website/site/content/docs/dev/development.md

@@ -206,9 +206,3 @@ publishing the release. However, for the nightly releases, this
 doesn't matter - everything must be automated here obviously. I also
 wanted the docker images to be built from the exact same artifacts
 that have been released at github (in contrast to being built again).
-
-
-# Background Info
-
-There is a list of [ADRs](@/docs/dev/adr/_index.md) containing
-internal/background info for various topics.