Added documentation (#17)

* Added documentation

* fixing review comments

README.md

@@ -1,5 +1,40 @@
 # pg_tde
 
+This is an experimental encrypted access method for Postgres 16.
+
+## Installation steps
+
+1. Build and install the plugin either with make or meson (see build steps)
+2. Add pg_tde to the preload libraries: `ALTER SYSTEM SET shared_preload_libraries = 'pg_tde';`
+3. Restart the postgres server
+4. Create the extension: `CREATE EXTENSION pg_tde;`
+5. Set the location of the keyring configuration file in postgresql.conf: `pg_tde.keyringConfigFile = '/where/to/put/the/keyring.json'`
+6. Create the keyring configuration file (see example keyring configuration)
+7. Restart the postgres server
+
+## Keyring configuration
+
+```json
+{
+        'provider': 'file',
+        'datafile': '/tmp/pgkeyring',
+}
+```
+
+Currently the keyring configuration only supports the file provider, with a single datafile parameter.
+This datafile is created and managed by Postgres, the only requirement is that postgres should be able to write to the specified path.
+
+This setup is intended for developmenet, and stores the keys unencrypted in the specified data file.
+
+## Build steps
+
+1. Install libjson-c-dev, for example on Ubuntu/Debian: `apt install libjon-c-dev`
+2. Install or build postgresql 16 (see reference commit below)
+3. If postgres is installed in a non standard directory, set the `PG_CONFIG` environment variable to point to the `pg_config` executable
+4. In the pg_tde directory: `make USE_PGXS=1` and `make USE_PGXS=1 install`
+
+## Base commit
+
 This is based on the heap code as of the following commit:
 
 ```