Make file format features non-default

It seems that most users only use a single file format and many forget
to disable default-features, leading to a uselessly inflated dependency
tree. This way around makes the library a tiny bit harder to get started
with, but I am willing to sacrifice this in order to save the world
some compile time.

.github/workflows/ci.yaml

@@ -26,7 +26,7 @@ jobs:
       uses: Swatinem/rust-cache@v2
     - name: Build
       run: cargo build
+    - name: Run tests with file formats
+      run: cargo test --features=toml,yaml,json5
     - name: Run tests
-      run: |
-        cargo test
-        cargo test --no-default-features
+      run: cargo test

Cargo.toml

@@ -34,7 +34,7 @@ required-features = ["toml"]
 
 
 [features]
-default = ["toml", "yaml", "json5"]
+default = []
 yaml = ["serde_yaml"]
 
 

src/lib.rs

@@ -8,6 +8,10 @@
 //!
 //! # How to use
 //!
+//! Add `confique` as dependency to your `Cargo.toml` and remember to enable the
+//! crate features for file formats you are interested in. For example:
+//! `cargo add confique --features=toml`.
+//!
 //! ## Defining your configuration with structs
 //!
 //! First, define some structs that describe all your configuration values. Use
@@ -154,12 +158,12 @@
 //!
 //! # Cargo features
 //!
-//! This crate has a Cargo feature for each supported file format which are all
-//! enabled by default to get started easily. If you don't need certain
-//! features, remember to disable them to save compile time:
+//! This crate has a Cargo feature for each supported file format. These are not
+//! enabled by default, so you have to specify which file formats you are
+//! interested in.
 //!
 //! ```toml
-//! confique = { version = "...", default-features = false, features = ["toml"] }
+//! confique = { version = "...", features = ["toml"] }
 //! ```
 //!
 //! All crate features: