Add documentation for Issue Search (#1111)

changes from forgejo/forgejo#6952

Reviewed-on: https://codeberg.org/forgejo/docs/pulls/1111
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: snematoda <snematoda.751k2@aleeas.com>
Co-committed-by: snematoda <snematoda.751k2@aleeas.com>

docs/user/index.md

@@ -38,6 +38,7 @@ involved in running it on their machines.
   - [Webhooks](./webhooks/)
   - [Programming language detection](./language-detection/)
   - [Code Search](./code-search/)
+  - [Issue Search](./issue-search/)
   - Authentication
     - [Generating an Access Token](https://docs.codeberg.org/advanced/access-token/)
     - [Access Token scope](./token-scope/)

docs/user/issue-search.md

@@ -0,0 +1,58 @@
+---
+title: Issue Search
+license: 'CC-BY-SA-4.0'
+---
+
+Since v11, Issue search on Forgejo replaced it's previously dropdown defined behaviour of searches with a query syntax defined by operators.
+
+## Query Syntax
+
+### Keywords
+
+1. Terms
+
+Performs a fuzzy match search of each term in the query.
+
+For example,
+
+- `foo` will return results that contain `foo`, or any of it's derivatives (such as `for` or `food`)
+- `foo bar` will return results that contain `foo` and/or `bar` or any of it's derivatives
+
+2. Phrase
+
+Performs an exact match for the provided phrase. This is done by wrapping the phrase in double quotes.
+
+For example,
+
+- `"foo"` will return results that contain an exact match of `foo`
+- `"foo bar"` will return results that contain an exact match of `foo bar`
+
+### Operators
+
+1. Negation
+
+Negates the keyword by returning results that does not contain the keyword. This is done by prefixing the keyword with a minus symbol.
+
+For example,
+
+- `-foo` will return results that does not contain `foo` or it's derivatives
+- `-"foo bar"` will return results that does not contain `foo bar`
+
+2. Required
+
+Denotes that the provided keyword MUST be present. This is done by prefixing the keyword with with a plus symbol.
+
+For example,
+
+- `+foo +bar` will return results that contain both `foo` and `bar` (or its fuzzy derivatives)
+- `+"foo" +"bar"` will return results that contain exactly both `foo` and `bar`
+- `+"foo bar" +"baz"` will return results that contain exactly both `foo bar` and `baz`
+
+### Escaping
+
+All operators may be escaped by adding a backslash in front of the operators.
+
+For example,
+
+- `"\"\""` will search for `""`
+- `\+1` will search for `+1`