doc(FAQ): refine MSRV policy

Cargo.toml

@@ -35,6 +35,8 @@ authors = [
     "Chloe Ross <[email protected]>",
     "Daniel Akhterov <[email protected]>",
 ]
+# TODO: enable this for 0.9.0
+# rust-version = "1.80.0"
 
 [package]
 name = "sqlx"

FAQ.md

@@ -20,23 +20,14 @@ For each database and where applicable, we test against the latest and oldest ve
 -------------------------------------------------------------------
 ### What versions of Rust does SQLx support? What is SQLx's MSRV\*?
 
-Officially, we will only ever support the latest stable version of Rust. 
-It's just not something we consider to be worth keeping track of, given the current state of tooling.
-
-Cargo does support a [`rust-version`] field now in the package manifest, however that will only ensure
-that the user is using a `rustc` of that version or greater; it does not enforce that the crate's code is
-actually compatible with that version of Rust. That would need to be manually enforced and checked with CI,
-and we have enough CI passes already.
-
-In practice, we tend not to reach for language or library features that are *too* new, either because
-we don't need them or we just worked around their absence. There are language features we're waiting to be
-stabilized that we want to use (Generic Associated Types and Async Traits, to name a couple) which we will
-be utilizing when they're available, but that will be a major refactor with breaking API changes 
-which will then coincide with a major release.
-
-Thus, it is likely that a given SQLx release _will_ work with older versions of Rust. However,
-we make no guarantees about which exact versions it will work with besides the latest stable version,
-and we don't factor MSRV bumps into our semantic versioning.
+SQLx's MSRV is the second-to-latest stable release as of the beginning of the current release cycle (`0.x.0`).
+It will remain there until the next major release (`0.{x + 1}.0`).
+
+This guarantees that SQLx will compile with a Rust version that is _at least_ six weeks old, which should be plenty
+of time for it to make it through any packaging system that is being actively kept up to date.
+
+We do _not_ recommend installing Rust through operating system packages, 
+as they can often be a whole year or more out-of-date.
 
 \*Minimum Supported Rust Version
 

rust-toolchain.toml

@@ -1,6 +1,4 @@
-# NOTE: this does NOT indicate a Minimum Supported Rust Version (MSRV) of SQLx.
-# We reserve the right to increase this version at any time without considering it to be a breaking change.
-# See the answer in FAQ.md for details.
+# Note: should NOT increase during a minor/patch release cycle
 [toolchain]
-channel = "1.80"
+channel = "1.78"
 profile = "minimal"