Added glossary docs (#868)

docs/user/glossary.md

@@ -0,0 +1,55 @@
+# Glossary
+
+Here we provide definitions for several commonly used Cursorless terms.
+
+## Action
+
+The action being performed on a target, such as `"chuck"` (to delete), `"post"` (to place your cursor after a target), etc.
+
+## Content range
+
+The [range](#range) containing the content of a target. This is the range that will be used when selecting a target, copying a target, as the source of a `"bring"` command, etc.
+
+## Domain
+
+The [range](#range) within which a [scope](#scope) is valid/active. For example, the scope type `"key"` is valid anywhere inside its containing key/value pair, and `"funk name"` is valid anywhere inside its containing function.
+
+## Iteration scope
+
+A canonical [range](#range) for a given [scope type](#scope-type) that defines a list of sibling [scopes](#scope). For example, the iteration scope for `"arg"` is an argument list. The iteration scope is used for things like `"every"`, to select all sibling scopes. This allows us to say things like `"take every arg"`, `"pre every line"`, etc.
+
+## Insertion delimiter
+
+The delimiter to be inserted before / after targets when inserting a new target. For example, for list items, the insertion delimiter is `", "`.
+
+## Leading / trailing delimiter range
+
+The leading delimiter range, if it exists, contains the delimiter before a [target](#target); the trailing delimiter range contains the delimiter after a target. For example, for a token with a hat over it, the trailing delimiter will be any whitespace after the token. For a function argument, it will be the trailing comma and any whitespace after the comma. Leading and trailing delimiters are used when constructing the [removal range](#removal-range), and can also be targeted directly using the `"leading"` / `"trailing"` modifiers.
+
+## Position
+
+A single position in a text document, consisting of `line` and `character` numbers/indices. A position is equivalent to a zero-length [range](#range) or zero-length [selection](#selection). Examples of positions include a cursor position, the start of your selection, the end of a function, etc.
+
+## Range
+
+A single range in a text document. Consists of `start` and `end` [positions](#position). Ranges have no direction, and `start` is always before, or, in the case of an empty range, equal to `end`. Examples of ranges include the range of a function, the whole document, a token with a hat over it, etc.
+
+## Removal range
+
+The range used when removing a [target](#target). This is generally the [content range](#content-range) plus one of the [leading or trailing delimiter ranges](#leading--trailing-delimiter-range), if they exist for the given target. For example, for a function call argument, the removal range will include a leading or trailing comma and whitespace, so that saying `"chuck arg"` or `"move arg"` will clean up the comma.
+
+## Scope type
+
+A predefined pattern/structure that can appear in a text document. This could be textual, like `line`, or `paragraph`, or syntactic, like `function` and `class`. Each scope type represents a way to view a text document in a structured manner, for example as a sequence of lines, or a hierarchy of statements (ie an `if` statement containing series of variable declarations). Scope types allow us to say things like `"take funk"` to select the function containing your cursor.
+
+## Scope
+
+A concrete instance of a given [scope type](#scope-type). For example, a particular function, line, or token in a text document.
+
+## Selection
+
+A directed selection in a text document. A selection is a [range](#range) with a direction. Contains `anchor` and `active` [positions](#position), where `active` is the position of the caret/cursor.
+
+## Target
+
+The thing being operated on by a Cursorless command, such as a function, a line, a function parameter, etc. For example, in the command `"chuck funk"`, the target will be the function containing your cursor.