Update cheatsheets

crystal

@@ -0,0 +1,41 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# crystal
+
+> Manage Crystal source code.
+> More information: <https://crystal-lang.org/reference/using_the_compiler>.
+
+- Run a Crystal file:
+
+`crystal {{path/to/file.cr}}`
+
+- Compile a file and all dependencies to a single executable:
+
+`crystal build {{path/to/file.cr}}`
+
+- Read Crystal source code from the command line or `stdin`, and execute it:
+
+`crystal eval '{{code}}'`
+
+- Generate API documentation from inline docstrings in Crystal files:
+
+`crystal docs`
+
+- Compile and run a Crystal specification suite:
+
+`crystal spec`
+
+- Start a local interactive server for testing the language:
+
+`crystal play`
+
+- Create a project directory for a Crystal application:
+
+`crystal init app {{application_name}}`
+
+- Display all help options:
+
+`crystal help`