update README.md for style and to avoid Swift version dependencies

Do not specifically refer to Swift 5.7.1 in README.md, to avoid having to
update it on every minor Swift update. Some small stylistic and syntactic
changes.

Author: lhoward

README.md

@@ -1,14 +1,15 @@
 # meta-swift
-Yocto meta-layer for swift-on-arm (Swift 5.7.1)
+
+Yocto layer for the Swift programming language.
 
 # Usage
 
-Add this meta layer to your project (refer to yocto user manual)
+Add this layer to your project (refer to Yocto user manual, or use `bitbake-layers add-layer`).
 
-Create a new swift application and include it in your yocto build as follows...
+Create a new Swift application and include it in your build as follows:
 
 ```
-DESCRIPTION = "My swift 5.7.1 app"
+DESCRIPTION = "My Swift app"
 LICENSE = "CLOSED"
 
 SRC_URI = "file://Sources/hello-world/main.swift \
@@ -18,14 +19,14 @@ SRC_URI = "file://Sources/hello-world/main.swift \
 inherit swift
 ```
 
-This does a few things, when you `inherit swift` meta-layer class, it will does the following...
+When you `inherit swift` class, it does the following:
 
-- Automatically download the x86_64 and ARMv7 swift 5.7.1 binaries and create a cross-compiling sys-root
-- Add an RDEPENDS_${PN} for `swift` which is the Armv7 runtime
+- Automatically download the x86\_64 SDK binaries and create a cross-compiling sysroot
+- Add an RDEPENDS:${PN} for `swift`
 - Performs the required build steps
 
 # Deployment
 
-The user of this meta-layer must provide their own `do_install` function.
+The user of this layer must provide their own `do_install` function.
 
-The finished binaries are located in ${WORKDIR}/.build/release/*
+The finished binaries are located in ${BUILD\_DIR}.