Update README about MSRV policy

See #89

Author: CBenoit

picky-asn1-der/README.md

@@ -2,6 +2,9 @@
 [![docs.rs](https://docs.rs/picky-asn1-der/badge.svg)](https://docs.rs/picky-asn1-der)
 ![Crates.io](https://img.shields.io/crates/l/picky-asn1-der)
 
+Compatible with rustc 1.43.
+Minimal rustc version bumps happen [only with minor number bumps in this project](https://github.com/Devolutions/picky-rs/issues/89#issuecomment-868303478).
+
 # picky-asn1-der
 
 Portions of project [serde_asn1_der](https://github.com/KizzyCode/serde_asn1_der) are held by

picky-asn1-x509/README.md

@@ -2,6 +2,9 @@
 [![docs.rs](https://docs.rs/picky-asn1-x509/badge.svg)](https://docs.rs/picky-asn1-x509)
 ![Crates.io](https://img.shields.io/crates/l/picky-asn1-x509)
 
+Compatible with rustc 1.43.
+Minimal rustc version bumps happen [only with minor number bumps in this project](https://github.com/Devolutions/picky-rs/issues/89#issuecomment-868303478).
+
 # picky-asn1-x509
 
 Provide implementation for types defined in [X.509 RFC](https://tools.ietf.org/html/rfc5280) and related RFC ([PKCS#8](https://tools.ietf.org/html/rfc5208), [PKCS#10](https://tools.ietf.org/html/rfc2986)).
@@ -11,3 +14,4 @@ This is a low-level library providing only raw types for serialization and deser
 These types are implementing `serde`'s `Serialize` and `Deserialize` and are to be used with [picky-asn1-der](https://crates.io/crates/picky-asn1-der).
 If you're looking for a higher level API, you may be interested by the [picky crate](https://crates.io/crates/picky) which uses
 this library internally and provides a nicer API.
+

picky-asn1/README.md

@@ -2,6 +2,9 @@
 [![docs.rs](https://docs.rs/picky-asn1/badge.svg)](https://docs.rs/picky-asn1)
 ![Crates.io](https://img.shields.io/crates/l/picky-asn1)
 
+Compatible with rustc 1.43.
+Minimal rustc version bumps happen [only with minor number bumps in this project](https://github.com/Devolutions/picky-rs/issues/89#issuecomment-868303478).
+
 # picky-asn1
 
 Defines wrappers for ASN.1 types:

picky/README.md

@@ -2,6 +2,9 @@
 [![docs.rs](https://docs.rs/picky/badge.svg)](https://docs.rs/picky)
 ![Crates.io](https://img.shields.io/crates/l/picky)
 
+Compatible with rustc 1.49.
+Minimal rustc version bumps happen [only with minor number bumps in this project](https://github.com/Devolutions/picky-rs/issues/89#issuecomment-868303478).
+
 # picky
 
 Portable X.509, PKI, JOSE and HTTP signature implementation.